The advent of virtual and augmented reality displays will completely reshape and better our lives in various aspects. The most suitable light sources to realize the corresponding displays have been believed to be micro-organic light-emitting diodes (µOLED) and micro-light-emitting diodes (µLED), respectively. In this talk, we will discuss the major technological challenge for each type; the electrical crosstalk in µOLEDs and the difficulty in achieving monochromatic and directional emission from µLEDs. We will also suggest the potential solutions to resolve these issues for both µOLEDs and µLEDs.

Devices based on organic semiconductors enable novel flexible, lightweight, and environmentally friendly electronics. A first success are organic light-emitting diode (OLED) displays, which have already reached a double-digit billion US$ market. I discuss challenges of materials and device research for successful products. In particular, I will discuss novel vertical transistors combined with OLED for very efficient devices for OLED display pixel driving. Furthermore, I will discuss highly ordered organic layers allowing efficient light emitting devices, but also organic transistors with greatly improved properties. In particular, we realized of the first organic bipolar transistors, preparing the way towards GHz organic electronics.

Halide perovskite are a versatile class of semiconductors with tunable optical and electronic properties. Halide perovskites have attracted great attention for their applications in solar cells, light-emitting diodes, lasers, and detectors. They exhibit remarkable properties such as high absorption coefficient, tunable bandgap, long carrier diffusion length, and low defect density. However, they also face challenges such as instability and hysteresis which can be traced to ionic migration. This work this talk will cover our efforts in halide perovskite light emitting diodes- specifically we will focus on how the electronic and ionic landscape of halide perovskite semiconductors can be tailored to emit blue emission. We also explain how through a judicious use of appropriate interfaces we are able to enable white light emitting diodes as well as diodes with time varying spectral output.

I will present a new iodine functionalized light emitting tris(2,4,6-trichlorophenyl) methyl (TTM) radical, which allows coupling of virtually any organic electron donor as well as acceptor moiety. We present a series of around 30 N-coupled donors and acceptors to TTM and explain why a medium strength donor gives the highest photoluminescence quantum yield. Moreover, I will elucidate the limits for tuning of the emission wavelength within the class of these N-donor coupled TTM emitters. These results will enable new design strategies for more stable and performant light emitting radicals and potentially allow us to expand the range of emission wavelength and overcome the current boundaries beyond the red spectrum.

OLEDs typically have a broad emission spectrum with an FWHM of more than 50 nm since π-conjugated organic semiconductors have strong vibronic coupling and structural relaxation when energy transitions from excited to ground states occur. Instead, Platinum- or Boron-based complexes with a rigid backbone shape allow us to overcome the limitations, making them attractive to meet the requirements for next-generation high-performance displays with high color purity. For example, tetradentate type Pt (II)- and Boron-Nitrogen-based complexes can induce narrow emission spectra with an FWHM less than 20 nm for RGB three colors, opening an extra room to extend the color gamut beyond the conventional fluorescent, Ir phosphorescent, and donor-acceptor type thermally activated delayed fluorescence (TADF) emitters. Notably, not only the color purity, Pt (II)- and Boron-Nitrogen-based complexes can achieve high efficiency, almost 100% internal quantum efficiency (IQE), by harvesting singlet and triplet excitons. However, Pt-phosphors typically suffer from triplet-triplet annihilation and triplet-exciton quenching due to the conversion of singlets into triplets via the intersystem crossing (ISC). Instead, multi-resonance (MR) induced TADF emitters based on the DABNA core with Boron and Nitrogen atoms can harvest singlets after reversely converting triplets into singlets via the reverse ISC (RISC), opening a chance to improve the device performance. Here, we developed color bure blue emitting MR emitters.

Spontaneous orientation polarization (SOP) reflects preferential molecular alignment leading to vertical orientation of permanent electric dipole moments (PDMs) and an overall polarization field. In OLEDs, SOP can induce carrier accumulation in the emissive layer, leading to exciton-polaron quenching (even at low-bias) that limits performance. We examine methods to engineer PDM alignment and mitigate the impact of SOP. We consider the behavior of blends of polar materials and the role of thin film processing conditions. The impact of deposition rate and substrate temperature are considered within a rate-temperature-superposition framework, providing a quantitative tool to predict SOP and its impact on OLEDs.

Helical conjugated polymers are of great interest for their potential as sources of circularly polarized luminescence for numerous electro-optical device applications including display technologies. Due to their relatively strong absorption cross sections and high emissivity in the visible wavelength range, these materials permit a detailed investigation of how the transition between helical and random coil forms are driven by polymer structural features such as chain length and chemical defects as well as environmental properties such as solvent and temperature. Bulk methods such as temperature dependent absorption, emission, and circular dichroism as well as single-particle microscopy are used to probe the helix-to-coil phase transition in a model chiral polyfuran and to determine whether the conformations favored in solution are retained in the solid state. In addition, the transient dynamics and the effects of chemical doping on the electronic properties of the helix and coiled forms are explored.

Colloidal quantum dots (QDs) are attractive materials for implementing solution-processable laser diodes. In addition to being compatible with inexpensive chemical techniques, they offer multiple advantages derived from a 0D character of their electronic states including size-tunable emission wavelengths and low optical-gain thresholds. Here we report on the realization of amplified spontaneous emission (ASE) with electrically driven QDs – an important milestone towards a QD laser diode. This effect is realized using compact, continuously graded QDs with strongly suppressed Auger recombination incorporated into a low-loss photonic waveguide integrated into a pulsed, high-current density light-emitting diode.

Organic semiconductors have the potential to be attractive laser materials and many optically pumped lasers have been demonstrated. However, electrical excitation is very challenging because of the low mobility of the materials, together with losses to triplets, polarons and contacts. We will discuss and compare approaches to electrically driven lasing, including the possibility of indirect pumping, and very promising results.

Organic-inorganic hybrid halide perovskites are exciting new semiconductors that show great promising in low cost and high-performance optoelectronics devices including solar cells, LEDs, photodetectors, etc. However, the poor stability is limiting their practical use. In this talk, I will present a molecular approach to the synthesis of a new family of organic-inorganic hybrid material - Organic Semiconductor-incorporated Perovskite (OSiP). Energy transfer and charge transfer between adjacent organic and inorganic layers are extremely fast and efficient, owing to the atomically-flat interface and ultra-small interlayer distance. Furthermore, this rigid conjugated ligand design dramatically enhances materials’ chemical stability and suppresses solid-state ion migration and diffusion, making them promising for real-world applications. Using this stable hybrid materials, we demonstrate the fabrication of high quality polycrystalline thin films and highly stable and efficient LED devices with suppressed ion migration and improved external quantum efficiency, color purity, and operational lifetime. Optically-driven nano lasers will be discussed briefly as well.

Phosphorescent organic light emitting diodes (PHOLEDs) feature high efficiency, brightness, and color tunability suitable for both display and lighting applications. However, overcoming the short operational lifetime of blue PHOLEDs remains possibly the most challenging problem in the field of organic electronics. Their short lifetimes originate from the annihilation of high energy, long-lived blue triplets that leads to molecular dissociation. Here, we introduce the polariton-enhanced Purcell effect to reduce the triplet density, and hence the probability for destructive high-energy triplet-polaron (TPA) and triplet-triplet annihilation (TTA) events. Besides the common optical modes in conventional devices, we couple triplets to plasmon-exciton-polaritons and cavity modes to significantly increase the strength of the Purcell effect. We achieve a four-fold improvement in LT95 (time to 95% of the initial luminance) of a blue PHOLED with a Purcell factor of 2.4. Furthermore, the chromaticity coordinates of a cyan emitting Ir-complex were shifted to (0.14, 0.14), a deep blue color suitable for displays. The power law between lifetime enhancement and the Purcell factor is between 1.4 and 2.2, suggesting contributions to degradation from both TPA and TTA. The polariton-enhanced Purcell effect and microcavity engineering provide new possibilities for extending the PHOLED lifetime, particularly in the deep blue spectral range essential for wide color gamut displays.

Creating and controlling macroscopic quantum states in solid-state materials have significant potential in developing quantum applications. Typical examples are superconductivity, Bose-Einstein condensation, and superfluorescence. Among these processes, superfluorescence provides a unique opportunity to monitor the evolution of an initially incoherent population of electronic excitations into macroscopic coherence in real-time. Recently we observed superfluorescence in lead halide perovskites at unprecedently high temperatures. In this talk, I will present time-resolved spectroscopic studies of the emergence of superfluorescence in perovskites, explaining the critical role of lattice dynamics in enabling this exotic quantum effect at unprecedentedly high temperatures.

Lead halide perovskites open great prospects for optoelectronics and a wealth of potential applications in quantum optical and spin-based technologies. Precise knowledge of the fundamental optical and spin properties of charge-carrier complexes at the origin of their luminescence is crucial in view of the development of these applications. On nearly bulk Cesium-Lead-Bromide single perovskite nanocrystals, which are the test bench materials for next-generation devices as well as theoretical modeling, we perform low-temperature magneto-optical spectroscopy to reveal their entire band-edge exciton fine structure and charge-complex binding energies. We demonstrate that the ground exciton state is dark and lays several millielectronvolts below the lowest bright exciton sublevels, which settles the debate on the bright-dark exciton level ordering in these materials. More importantly, combining these results with spectroscopic measurements on various perovskite nanocrystal compounds, we show evidence for universal scaling laws relating the exciton fine structure splitting, the trion and biexciton binding energies to the band-edge exciton energy in lead-halide perovskite nanostructures, regardless of their chemical composition. These scaling laws solely based on quantum confinement effects and dimensionless energies offer a general predictive picture for the interaction energies within charge-carrier complexes photo-generated in these emerging semiconductor nanostructures.

All-inorganic lead-halide perovskite (CsPbX3, X = Cl, Br, I) quantum dots (QDs) have emerged as a competitive platform for various optoelectronic applications e.g., LEDs featuring narrow emission and quantum light sources. Many-body interactions and quantum correlations among photogenerated exciton complexes play an essential role, e.g., by determining the laser threshold, the overall brightness of LEDs, and the single-photon purity in quantum light sources. In this work, by combining single-QD optical spectroscopy performed at cryogenic temperatures in combination with configuration interaction (CI) calculations, we address the trion and biexciton binding energies and unveil their peculiar size dependence. We find that trion binding energies increase from 7 meV to 17 meV for QD sizes decreasing from 30 nm to 9 nm, while the biexciton binding energies increase from 15 meV to 30 meV, respectively. CI calculations quantitatively corroborate the experimental results and suggest that the effective dielectric constant for biexcitons slightly deviates from the one of the single excitons, potentially as a result of coupling to the lattice in the multiexciton regime. Our findings provide a deep insight into the multiexciton properties in all-inorganic lead-halide perovskite QDs, essential for classical and quantum optoelectronic devices.

Hybrid semiconductor materials are predicted to lock chirality into place and encode asymmetry into their electronic states, while the softness of their crystal lattice accommodates lattice strain and maintains high crystal quality with the low defect densities necessary for high luminescence yields. The realization of chiral bulk emitters with bright circularly-polarized luminescence from such materials is desired for the design of chiroptical photonic and opto-spintronic applications. Here, we report photoluminescence quantum efficiencies (PLQE) as high as 39%, and degrees of circularly polarized photoluminescence of up to 52%, at room temperature, in the chiral layered hybrid lead-halide perovskites (R/S/Rac)-3BrMBA2PbI4 (3BrMBA = 1-(3-Bromphenyl)-ethylamine). Using x-ray diffraction and density-functional theory we elucidate the detailed chirality transfer mechanism from chiral crystal structures to spin-orbit-split band structures. Using state-of-the-art transient chiroptical spectroscopy, we rationalize the excellent photoluminescence yields from suppression of non-radiative loss channels and very high rates of radiative recombination. We further find that photo-excitations sustain polarization lifetimes that exceed the timescales of radiative decays, which rationalize the high degrees of polarized luminescence. We postulate that the superior optoelectronic properties of the layered hybrid perovskites arise from their special tolerance to crystal structure chirality, which we carefully designed by cation engineering. Our findings pave the way towards high-performance solution-processed photonic systems for chiroptical applications and chiral-spintronic logic at room temperature.

This talk will summarize a number of current efforts in our group to realize organic electroluminescence in devices with unconventional form-factors, powering strategies, and mechanical characteristics. Examples include our extensive work on the monolithic integration of OLEDs on CMOS backplanes with extreme aspect ratios, which allows dense, pixelated arrays via direct physical vapour deposition of organic semiconductors on functional silicon. Furthermore, recent progress in development of miniature OLEDs with wireless power supply is introduced. This work uses the magneto-electric effect instead of the traditionally used RF coils. Again, direct deposition, in this case on the power harvesting material, enables substantially more compact devices than alternative inorganic approaches. Finally, liquid-type electro-chemiluminescent devices are introduced that can be fabricated in an extremely facile manner by injecting a solution of suitable organic semiconductors through a microfluidic channel into a pre-fabricated cell with opposite electrodes. The development of a new emission pathway allows us to dramatically improve the brightness and efficiency of these devices over the state-of-the-art.

Hybrid metal halide perovskite has emerged as a remarkable light-emitting material for photonic devices ranging from lasers, LEDs, photodetectors (PDs), and photonic metamaterials. While the demonstration of electrically pumped lasing from perovskite is still elusive, optically pumped continuous wave (CW) lasing is a necessary intermediate step to achieve this goal. We show green lasing under quasi-CW optical pumping at Peltier-cooling accessible 260K, from a directly patterned and encapsulated MAPbBr3 photonic crystal cavity. In the meantime, Hyperbolic metamaterial (HMM) is a special class of anisotropic material that has drawn tremendous research attention recently, as it exhibits metal and dielectric features at the same time. This unique feature allows HMMs to be used in applications such as super-resolution imaging, spontaneous emission enhancement, and topological photonics. However, due to the inherent loss from the metal constituent, HMM’s insertion into these applications is hindered. In order to overcome this hurdle, we show a luminescent MAPbI3 perovskite/Au HMM, wherein the dielectric constituent is fully composed of perovskite gain, thus compensating for the metal loss. In terms of PDs, the main challenge in perovskite PDs is to simultaneously achieve high responsivity and fast speed. By employing a directly patterned nanograting MAPbI3 metal-semiconductor-metal (MSM) perovskite PD on interdigitated ITO electrodes. Because of the improved perovskite morphology after directly patterning, as well as the enhanced electric field intensity by the perovskite nanograting and interdigitated electrodes, our perovskite PDs have high responsivity, short response time, and high detectivity, all of which are among the best performance in MSM perovskite PDs. Moreover, our perovskite PDs maintain excellent photocurrent performance after 20 days of air exposure. We believe the integration of these directly patterned perovskite devices can enable all-perovskite photonic integrated circuits.

Here, we present a silicone engineered anisotropic lithography of the organic light-emitting semiconductor (OLES) that in-situ forms a non-volatile etch-blocking layer during reactive ion etching. [1,2] This unique feature not only slows the etch rate but also enhances the anisotropy of etch direction, leading to gain delicate control in forming ultrahigh-density multicolor OLES patterns (up to 4,500 pixels per inch) through photolithography. This patterning strategy inspired by silicon etching chemistry is expected to provide new insights into ultrahigh-density OLEDoS (OLED on Silicon) microdisplays.

The next generation of advanced displays must have flexible form factors and high-definition red, green, and blue (RGB) pixels. Here, we demonstrate full-color, ultrahigh-resolution nanocrystal patterning for ultrathin wearable displays. The development of double-layer dry transfer printing of the PeNC and organic charge transport layers prevent internal cracking during the transfer printing procedure. As a result, 100% transfer yield RGB pixelated PeNC patterns with up to 2,550 PPI and monochrome patterns with up to 22,450 PPI are produced. The perovskite light-emitting diodes (PeLEDs) with transfer-printed active layers demonstrate exceptional electroluminescence properties and have the highest reported external quantum efficiency of printed PeLEDs at 14.8%. Moreover, the manufacture of extremely thin multi-color PeLEDs is made possible by double-layer transfer printing.

In this talk, we will discuss on what needs to be done to tailor OLEDs to meet the requirements for various wearable healthcare applications. First of all, we will introduce some of our recent works on Pt-based phosphorescent emitters for near-infrared OLEDs and discuss their potential applications in healthcare. We will then present our progress in body-attached low-power pulse oximetry sensors based on OLEDs and OPDs. Furthermore, we will describe some of the recent results obtained with ultraflexible OLEDs packaged with biocompatible materials and will present the extension of their applications to non-conventional areas such as internal photobiomodulation.

The vast amount of biological mysteries and biomedical challenges faced by humans provide a prominent drive for seamlessly merging electronics with biological living systems (e.g. human bodies) to achieve long-term stable functions. Towards this trend, one of the key requirements for electronics is to possess biomimetic form factors in various aspects for achieving long-term biocompatibility. To enable such paradigm-shifting requirements, polymer-based electronics are uniquely promising for combining advanced electronic functionalities with biomimetic properties. Among all the functional materials, stretchable light-emitting materials are the key components for realizing skin-like displays and optical bio-stimulation. In this talk, I will mainly introduce our research in imparting stretchability onto “third-generation” electroluminescent polymers that can harness all the excitons through thermally activated delayed fluorescence (TADF), thereby with a theoretical near-unity quantum yield and high OLED efficiency. Our developments of fully stretchable OLED devices show the promise of achieving all the desired EL and mechanical characteristics, including high efficiency, brightness, switching speed, stretchability, and low driving voltage.

An is-OLED (intrinsically stretchable organic light-emitting diode) can be stretched or deformed without losing its electronic properties or physical integrity. With their unique properties, intrinsically stretchable OLEDs have the potential to open up new avenues for the development of innovative technologies such as wearable electronics, biomedical devices, and stretchable displays. However, most studies showed low efficiency and stability. Hence, we designed a solution-processable and intrinsically stretchable electron transport layer (is-ETL) by blending additive and electron transport materials. The combination of additives to increase the mechanical properties and electron transport materials to increase the electrical properties resulted in efficient and stable is-OLEDs.

Carboranes are polyhedral clusters with unusual molecular bonding and electronic properties. The icosahedral C2B10H12 carborane exists as either the para (p), meta (m), or ortho (o) isomer, with an increasing polarity and electron-withdrawing nature as the carbon atoms are positioned closer to each other. Here we examine the effects of the inclusion of different caborane isomers into a range of linear and non-linear aromatic systems and polymers, focusing on their photoluminescence properties.

Hyperfluorescence shows great promise for the next generation of commercially feasible blue organic light-emitting diodes (OLEDs). High-gap matrices are currently the only available approach to suppress Dexter transfer to terminal emitter triplet states to approach the required levels of efficiency and stability, which unfortunately leads to overly complex device structures from a fabrication standpoint. To eliminate the need for matrices, we introduce a molecular design strategy where ultra-narrowband blue emitters are covalently encapsulated by insulating alkylene straps. OLEDs with simple emissive layers consisting of pristine thermally activated delayed fluorescence (TADF) hosts doped with encapsulated terminal emitters exhibit negligible external quantum efficiency (EQE) drops compared to non-doped devices, enabling an unprecedented maximum EQE of 21.5%. Simultaneously, ultra-narrow electroluminescence half-widths are afforded (14–15 nm) at desirable deep blue peak wavelengths (449 and 458 nm). To explain the near 100% internal quantum efficiency (IQE) in the absence of high gap matrices, we turn to transient absorption spectroscopy. Dexter transfer to terminal emitter triplets is directly observed for the first time in a hyperfluorescent system through comparison with a non-encapsulated analogue. It is unequivocally concluded that Dexter triplet transfer from a pristine TADF sensitiser host can be substantially reduced by an encapsulated terminal emitter, opening the door to highly efficient ‘matrix-free’ blue hyperfluorescence.

Circularly polarized light-emitting diodes (CP-LEDs) are crucial for applications including 3D and glare-free displays, and chiral sensing. Most research to date has focused on developing circularly polarized (CP) emitters that can inherently emit CP light. However, the impact of the electromagnetic environment within the thin-film geometry of CP-LEDs on chiroptical properties is often overlooked, leading to discrepancies in the chiroptical properties between isolated CP emitters and CP-LED incorporating these emitters. We present a theoretical method for accurately modeling CP-LEDs that employ a CP emitter, described as one of two types of coherent superpositions of linearly polarized dipoles oscillating with a phase difference of π/2: an electric and magnetic dipole (Type I) parallel to each other or two orthogonal electric dipoles (Type II). Type I represents an idealized, structurally chiral material, which has been the primary focus of the development of CP emitters thus far, while Type II corresponds to emission resulting from radiative recombination of carriers with specific spins or orbital angular momenta. Based on our calculations, we provide design strategies for CP-LEDs that possess both a high dissymmetry factor and a high quantum efficiency.

We demonstrate ultralong room temperature phosphorescence from aggregates of an organic semiconductor by managing competing effects of aggregate-induced enhancement and quenching with a simple and scalable processing technique. These results are in contrast to conventional ultralong room temperature phosphors which employ single crystals or isolated molecules in a rigid host, thus imposing deleteriously strict molecular design and processing constraints. The photophysical mechanisms for aggregate-enhanced emission and quenching are discussed.

In this work, we dope Mn2+ ions into an organic-inorganic hybrid quasi-bulk 3D perovskite with the addition of tris(4-fluorophenyl)phosphine oxide (TFPPO) dissolved in a chloroform antisolvent to achieve green perovskite LEDs (PeLEDs) with a 14.0% EQE and a 128,000 cd/m2 peak luminance. While TFPPO dramatically increases the PeLEDs’ EQE, the operational stability is compromised. At 5mA/cm2, our PeLED fabricated with a pure chloroform antisolvent (EQE=2.97%) decays to half of its maximum luminance in 37.0 minutes. Alternatively, our PeLED fabricated with TFPPO (EQE=14.0%) decays in 2.54 minutes. Consequently, we studied both photophysical and optoelectronic characteristics before and after PeLED electrical degradation.

Transfer printing is a promising method for creating ultrahigh-resolution red, green, and blue (RGB) pixel arrays of lighting-emitting nanocrystals, enabling exploitation of their unique properties. We demonstrated successful fabrication of high-resolution RGB pixel arrays and ultrahigh-resolution patterns (2550 ppi) for both conventional quantum dots and perovskite nanocrystals. In addition, light-emitting diodes employing the printed nanocrystals exhibit excellent device performances, leading to new breakthroughs in display technology.

We have demonstrated silicone-incorporated organic light-emitting semiconductor (SI-OLES) enabling anisotropic micro-lithography with reactive ion etching (RIE)-coupled photolithography (RCP) process. The SI-OLES possesses high chemical–physical robustness, and particularly, can render silicone-based non-blocking etching layer during the RIE by mimicking RIE chemistry of silicon, so that precise anisotropic mciro-patterns of SI-OLES can be achieved by the RCP process. Consequently, we successfully fabricated ultrahigh-density RGB OLES anisotropic patterns (4,216 ppi corresponding to 4,938,271 patterns/cm2), as well as, full-color SI-OLES-based OLEDs (949 ppi) without degradation of their electroluminescence characteristics, by the application of three cycles of consecutive RCP processes.

A compact active-matrix organic light-emitting diode (AMOLED) micro-display is demonstrated by using Ag/MoS₂/Ag-based memristive electrodes as the top (cathode) and bottom (anode) electrodes. The anode serves as a reflector with functions of the transistor and capacitor in the conventional AMOLED driving circuit; thus, each OLED pixel is turned on or off according to its resistance state, without any switching elements, making the driving system compact. Meanwhile, the cathode is designed as a semi-transparent electrode by properly adjusting the thickness of the MoS₂ and Ag layers. This approach paves the way for implementing a compact driving circuitry in various display systems.

The design space of second-order distributed feedback (DFB) resonators is studied by exciting lasing from a lead halide perovskite film over high-quality, rectangular gratings fabricated in a 200mm fab. The dependence of the lasing threshold on the physical parameters of the grating are systematically studied and modelled. This model is subsequently applied to study the cavity size optimization which is relevant for scaled, electrically pumped devices. We elaborate our design strategy, and demonstrate optically pumped lasing from a cavity as short as 50 micrometers, without significantly raising the lasing threshold.

Dynamic behaviors for light emission of one- and two-photon excitation in single crystalline perovskite bulks with metallic and dielectric-nanoparticles hybrid configurations are experimentally examined. Thereby, a series of comprehensive simulations are conducted for investigating the feasible mechanism and the relevant interactions in such sophisticated configurations. Under one-photon excitation, optical pumping fluences can only irradiate and penetrate in the skin depths of single crystalline perovskite-nanoparticle hybrid configurations; therefore, the corresponding light-emitting performance of hybrid configuration mixed with Au NPs can be ameliorated due to a stronger scattering field of Au NPs than that of SiO2 NPs. On the other hand, under two-photon excitation, optical pumping fluences can irradiate and penetrate much deeper; hence, the corresponding light-emitting performance of hybrid configurations mixed with both Au NPs and SiO2 NPs can be improved. However, owing to the shadowing effect of Au NPs, optical pumping fluences and the corresponding light-emitting in the interior regions will be shielded. Consequently, the overall light-emitting performance is slightly lower than that mixed with SiO2 NPs. We investigate the feasible mechanism in such sophisticated configurations and identify the relevant interactions between NPs and MAPbBr3 perovskite material, providing proper interpretations for a deeper understanding of the dynamic behaviors of one- and two-photon light emission in such single crystalline perovskite-nanoparticle hybrid configurations, paving a new route in nonlinear optics.

In this work, the exciton diffusion model coupled with a drift-diffusion solver is used to simulate three bilayer TTF-OLEDs devices, which triplet tank layer (TTL) is DMPPP (Device A), DCPPP (Device B), and PPC (Device C), respectively. The simulation results are matched to the experimental data, and the efficiency and loss mechanisms are studied. The main reason for IQE loss is triplet-polaron quenching (TPQ) and the ability of triplet diffusion. The experimental result of the device has a recorded 15.5% efficiency in TTF OLEDs, which are benefitted due to the high diffusion coefficient and fewer electrons accumulated in the converting layer to avoid the TPQ processes. This is due to the LUMO of PPC being matched to the second layer to avoid carrier accumulation at the interface. Device A has a good diffusion ability and low TPQ coefficients but suffers from electron accumulation at the interfaces. The worst case (B) has a low diffusion coefficient with a high TPQ coefficient, which has a weak triplet density in the NPAN layer to induce the TTF processes. Besides the bilayer studies, the single-layer structures are also studied to extract some key parameters for bilayer studies. It is interesting to find that material with high TPQ coefficients can quench the triplets to stop the triplet-singlet annihilation, which will have a higher efficiency in the single-layer material. However, it plays the opposite role in bilayer structures because triplets are quenched before they reach the NAPA layers.