High-efficiency Devices Research Articles

Ultra-Low Loss and Ultra-Compact Polarization-Insensitive SOI Multimode Waveguide Crossing Based on an Inverse Design Method

Polarization-insensitive waveguide crossings are indispensable components of photonic integrated circuits (PICs), enabling the concurrent computing of optical signals from diverse waveguides inside the limits of a restricted spatial footprint. Leveraging mirror symmetry direct binary search, we successfully demonstrate an ultra-compact and ultra-low loss polarization-insensitive waveguide crossing that achieves insertion losses below −0.11 dB and crosstalk levels beneath −22.6 dB for transverse electric (TE) mode, as well as insertion losses below 0.05 dB and crosstalk levels beneath −24.5 dB for transverse magnetic (TM) mode across the C-band with a footprint of 3 × 4 μm2. The results confirm that this mirror symmetry optimization method yields high-efficiency devices while reducing computational time. We believe this high-efficiency polarization-insensitive waveguide crossing can have potential applications in dense PIC systems.

Application of Smart Condensed H-Adsorption Nanocomposites in Batteries: Energy Storage Systems and DFT Computations

A comprehensive investigation of hydrogen grabbing towards the formation of hetero-clusters of AlGaN–H, Si–AlGaN–H, Ge–AlGaN–H, Pd–AlGaN–H, and Pt–AlGaN–H was carried out using DFT computations at the CAM–B3LYP–D3/6-311+G (d,p) level of theory. The notable fragile signal intensity close to the parallel edge of the nanocluster sample might be owing to silicon or germanium binding-induced non-spherical distribution of Si–AlGaN or Ge–AlGaN hetero-clusters. Based on TDOS, the excessive growth technique of doping silicon, germanium, palladium, or platinum is a potential approach to designing high-efficiency hybrid semipolar gallium nitride devices in a long-wavelength zone. Therefore, it can be considered that palladium or platinum atoms in the functionalized Pd–AlGaN or Pt–AlGaN might have more impressive sensitivity for accepting the electrons in the process of hydrogen adsorption. The advantages of platinum or palladium over aluminum gallium nitride include its higher electron and hole mobility, allowing platinum or palladium doping devices to operate at higher frequencies than silicon or germanium doping devices. In fact, it can be observed that doped hetero-clusters of Pd–AlGaN or Pt–AlGaN might ameliorate the capability of AlGaN in transistor cells for energy storage.

High-Performance Narrowband Pure-Green OLEDs with Gamut Approaching BT.2020 Standard: Deuteration Promotes Device Efficiency and Lifetime Simultaneously.

In order to fulfill the demand for ultrahigh definition organic light-emitting diodes (OLEDs), pure-green emitters with Commission Internationale de l'Éclairage (CIE) y-coordinate over 0.71 are in urgent demand. Meanwhile, the high device efficiency, small efficiency roll-off, and operational lifetime also remain challenging issues. In this work, a series of narrowband pure-green fluorescent emitters based on a double-boron (B) doped polycyclic aromatic hydrocarbons (PAHs) framework fused with naphthalene units is reported. The newly designed emitters realize green emission with peaks of 512-521nm and extremely narrow full-width at half-maxima (FWHMs) of 16-17nm in toluene solution. Utilizing these emitters in a phosphor-sensitized fluorescence (PSF) system, the resulting OLEDs exhibit pure green emission with peaks in the range of 514-526nm and very narrow FWHMs of 19-20nm. Notably, the devices based on the partially deuterated emitter, DBN-NaPh-d, not only achieve a maximum external quantum efficiency (EQEmax) as high as 35.2%, small efficiency roll-off, along with a CIEy of 0.74 but also showcase impressive operational stability with a long lifetime (LT50) of over 3000h at an initial luminance of 1000cdm-2. This work represents one of the highest device efficiencies and superior device stability among fluorescence emitter-based OLEDs.

High-Performance and Environmentally-Friendly Bulk-Wave-Acoustofluidic Devices Driven by Lead-Free Piezoelectric Materials.

Bulk-wave-acoustofluidic devices provide strong acoustic fields and high device efficiency, thereby offering high-throughput capability when processing biological samples. Such devices are typically driven by lead zirconate titanate (PZT) transducers, which contain a high content of lead, inevitably resulting in environmental and biocompatibility issues. Replacing PZT with lead-free piezoelectric materials in various ultrasonic devices is considered challenging mainly due to the inferior piezoelectric properties lead-free materials possess compared to those of PZT. In this study, through both experiments and numerical simulations, it is demonstrated that the performance of the bulk-wave-acoustofluidic devices driven by (Bi,Na)TiO3-BaTiO3-(Bi,Na)(Mn,Nb)O3 (BNT-BT-BNMN) can match that of PZT-driven devices at low power and is superior at intermediate power. It is found that the low acoustic impedance and the weak transverse mode in BNT-BT-BNMN compensate for the inferior piezoelectric properties at low power. The fact that the BNT-BT-BNMN devices outperform at intermediate power is consistent with the superior performance of the Mn-doped BNT-based piezoelectric materials compared to PZT at high power. Perfect focusing on 5- -diameter polystyrene particles at a flow rate of up to 10 mL min-1 is achieved using the BNT-BT-BNMN device at input power of 1W.

Design and analysis of inorganic tandem architecture with synergistically optimized BaSnS3 top and AgTaS3 bottom perovskite Sub-Cells

Perovskite materials are revolutionizing the solar cell (SC) industry, continually enhancing their properties and establishing a prominent photovoltaic technology. Among these, BaSnS3 (BTS) and AgTaS3 (ATS) stand out for their strong potential as absorber layers. These inorganic chalcogenide perovskites address the drawbacks of their organic counterparts, being both lead-free and non-toxic, thereby making them highly suitable for photovoltaic (PV) applications. The exploration of BTS and ATS as absorber layers in a tandem solar cell’s top and bottom cells has yielded remarkable outcomes. The innovative tandem solar cell design features a top cell structured as n-WS2/p-BaSnS3/p+-MoS2 and a bottom cell configured as n-WS2/p-AgTaS3/p+-GeS. This theoretical study using SCAPS-1D demonstrates a high efficiency of 42.57 % with a VOC of 2.03 V, a JSC of 23.29 mA/cm2, and an FF of 89.85 %. These impressive results are achieved with adjusted layer thickness, carrier doping and defect levels, highlighting the strong potential of BaSnS3 and AgTaS3 photoactive materials. The findings reveal the viability of innovative, all-inorganic perovskite-based tandem solar cells, offering a promising avenue for future sustainable and high-efficiency photovoltaic device technologies.

Tuning band gap and improving optoelectronic properties of lead-free halide perovskites FrMI3 (M = Ge, Sn) under hydrostatic pressure

In the field of optoelectronic applications, inorganic cubic halide perovskites have turned into a leading choice for commercialization. The physical properties of cubic FrMI3 (M = Ge, Sn) halide perovskites under pressure are explored at multiple pressures up to 10 GPa using ab initio Density-Functional Theory due to their significant importance. The structural accuracy, reflected in lattice parameters and unit cell volume, closely corresponds to previously reported data. FrGeI3 and FrSnI3 exhibited direct electronic band gaps of 0.65 eV and 0.46 eV with GGA-PBE functional, respectively, indicating their semiconducting nature at 0 GPa. The enhanced band gaps obtained employing the HSE06 potential are 1.61 eV and 1.28 eV for the corresponding perovskites. FrGeI3 and FrSnI3 shift from semiconducting to metallic states under pressures of 4.5 GPa and 3 GPa, respectively, thereby enhancing the conductivity. Pressure also improves optical functions, indicating both perovskites may be employed in high-efficiency optoelectronic devices that operate within the visible and ultra-violet (UV) range. At 10 GPa pressure, both FrGeI3 and FrSnI3 demonstrate the sharpest absorption spikes in the UV region, approximately at 2.61 × 105 cm−1 and 2.42 × 105 cm−1, respectively, resulting in sharp peaks in optical conductivity of approximately 5.98 1/fs for FrGeI3 and 5.49 1/fs for FrSnI3. FrGeI3 consistently outperforms FrSnI3, offering superior electronic and optical characteristics. Additionally, pressure modifies the mechanical features of entitled perovskites while conserving stability. The anisotropic and ductile properties become more pronounced under pressure. The outcomes of this study are expected to propel the advancement of lead-free optoelectronic devices, driving innovation in sustainable energy solutions.

OLUFF: a novel set of ground and excited state force field parameters of the emitting oxyluciferin species.

The modeling of the bioluminescent system of fireflies is key to understand the binding mode of the oxyluciferin/luciferase complex and its photophysical properties with the aim of developing high-efficiency devices and techniques. In this work, we present the OLUFF force field, which is able to describe the interactions to sample the conformational space of the four possible oxyluciferin emitters in both ground and excited state. This force field has been parameterized to reproduce quantum mechanical (QM) energies and geometrical parameters. Moreover, it has been validated by comparing probability distribution functions, minimized structures, infrared spectra and normal mode analysis obtained from OLUFF-based molecular dynamic (MD) simulations with their QM counterparts. Additionally, ground state simulations have also been performed using the general amber force field (GAFF) and compared with the OLUFF. It has been demonstrated that the OLUFF not only reproduces well the QM properties, but also improves the results from the GAFF.

An efficient extraction device for microplastics in marine sediments and its applications.

Microplastics, defined as small pieces of plastic with a size less than 5 millimeters, constitute a significant sink for microplastics in marine sediments. Given the potential harm to nature and human beings, accurate detection of microplastics in marine sediments is of the utmost importance. The separation of microplastics from marine sediments represents a pivotal step in the quantitative detection of microplastics. This paper presents a high-efficiency extraction device for microplastics in marine sediments, with the objective of enhancing the effectiveness and efficiency of microplastics extraction. The device employs an air pump to thoroughly mix the samples and incorporates metal perforated plate fillers to achieve efficient sedimentation, thus facilitating the separation of microplastics from the surrounding marine sediments. Subsequently, the separated microplastics are passed through a series of pore sizes of stainless steel screens and glass fibre filters via suction filtration, allowing for the collection of microplastics of varying particle sizes for subsequent identification. Following a series of method trials, the optimal extraction conditions for this device were identified. The results demonstrated its excellent extraction effectiveness and high efficiency. To verify the feasibility of this device, it was used to investigate the microplastics in the sediments of Dongzhai Harbor, Hainan. The abundance, particle size distribution, shape, and composition of microplastics in the sediments of this area were obtained, which not only validated the practicality of this microplastic extraction device but also provided significant insights for ecological and environmental protection in the region.

Mitigating Slow Reverse ISC Rates in TAPC-PBD Exciplex via Rapid Förster Energy Transfer to TTPA

There have been many advances in the development of thermally activated delayed fluorescence (TADF) materials for organic light emitting diode (OLED) applications in recent years. In particular, intramolecular exciplex systems have been highly studied and found to produce OLED devices of high external quantum efficiency (EQE) due to triplet harvesting via TADF. The proposed next generation of OLEDs uses hyperfluorescence to overcome the problem of broad emission associated with exciplexes. This process involves Förster resonance energy transfer (FRET) from the TADF host to a fluorescent dopant. In this work we revisited the photophysics of the TAPC:PBD exciplex (formed between the electron donor di-[4-(N,N-di-p-tolyl-amino)-phenyl]cyclohexane (TAPC) and the electron acceptor, 2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD)) as a host capable of simultaneously performing triplet harvesting and work as a donor transferring energy to a bright fluorescent emitter. The aim is to investigate the interplay between energy transfer and intersystem crossing in this hyperfluorescence system. Contrarily to previous findings, films of the TAPC:PBD blend show relatively slow reverse intersystem crossing rate (RISC) and weak luminescence efficiency (PLQY). Despite this, when doped with the strong fluorescent emitter TTPA, the luminescence quantum yield is greatly improved due to the highly efficient energy transfer rate from TAPC:PBD to TTPA. The rapid FRET from the exciplex to the fluorescent emitter overcomes the non-radiative losses affecting the luminescence efficiency of the blend. This study shows that the hyperfluorescence mechanism not only allows colour purity in OLEDs to be optimised, but also facilitates suppressing major loss mechanisms affecting luminescence efficiency, thus creating conditions to maximizing EQE.

Observation of Spin Splitting in Room-Temperature Metallic Antiferromagnet CrSb.

Recently, unconventional antiferromagnets that enable the spin splitting (SS) of electronic states have been theoretically proposed and experimentally realized, where the magnetic sublattices containing moments pointing at different directions are connected by a novel set of symmetries. Such SS is substantial, k-dependent, and independent of the spin-orbit coupling (SOC) strength, making these magnets promising materials for antiferromagnetic spintronics. Here, combined with angle-resolved photoemission spectroscopy (ARPES) and density functional theory (DFT) calculations, a systematic study on CrSb, a metallic spin-split antiferromagnet candidate with Néel temperature TN = 703 K, is conducted. The data reveal the electronic structure of CrSb along both out-of-plane and in-plane momentum directions, rendering an anisotropic k-dependent SS that agrees well with the calculational results. The magnitude of such SS reaches up to at least 0.8eV at non-high-symmetry momentum points, which is significantly higher than the largest known SOC-induced SS. This compound expands the choice of materials in the field of antiferromagnetic spintronics and is likely to stimulate subsequent investigations of high-efficiency spintronic devices that are functional at room temperature.

Achieving 11.23 % efficiency in CZTSSe solar cells via defect control and interface contact optimization

The high open-circuit voltage deficit (VOC, def) caused by structural imperfections in the absorber layer and charge loss during carrier transport is a critical barrier affecting the performance of Cu2ZnSn(S,Se)4 (CZTSSe) devices. In this work, Ag was added to the DMF-based Cu+-Sn4+ system, which significantly improved the crystal morphology and electrical properties of the absorber layer. Additionally, optimizing the selenization process not only reduced surface roughness and eliminated voids at the bottom of the absorber layer but also resulted in the formation of a MoSe2 back interface layer with a more suitable thickness. These measures collectively enhanced the overall quality of the absorber layer, reducing the formation of deep-level defect clusters and effectively boosting carrier transport efficiency. Consequently, the concentration of bulk and interfacial defects decreased, and the impact of potential barriers on carrier movement was minimized. With these comprehensive improvements, the power conversion efficiency of CZTSSe solar cells increased from 8.48 % to 11.23 %. Our research demonstrates that optimizing the structure of the absorber layer can effectively enhance the performance of CZTSSe solar cells, providing valuable insights for the fabrication of high-efficiency devices in the future.

Reversing band bending at grain boundaries enables high-efficiency Cu2ZnSn(S,Se)4 solar cells

Kesterite solar cells show great potential for sustainable photovoltaic technology, attributed to their excellent semiconductor properties and earth abundant composition. However, undesirable band bending at the grain boundaries (GBs) in Cu2ZnSn(S,Se)4 (CZTSSe) films induces serious carrier recombination because of inhomogeneous distribution of S and Se in the grain interiors (GIs) and at GBs, which results in large open-circuit voltage deficit and overall poor performance of CZTSSe solar cells. Here, a robust hydrothermal sulfurization design has successfully inverted the band bending at the GBs, with advanced cathodoluminescence measurement confirming the transition of carrier collection pathways from the GBs to the GIs, thereby achieving efficient carrier collection within the GIs. Simultaneously, this design has effectively passivated the non-radiative recombination in the GIs, smoothing the way for carrier collection. Ultimately, a 13.7 % efficiency CZTSSe solar cell with 44 % improvement is realized by this process. This study discloses that reversing the band bending at GBs is practical to tailor the carrier collection, and thus pave the pathway for high-efficient photoelectronic devices.

Optimization of collection efficiency for a dual-row jet mining machine based on CFD-DEM coupling

Deep-sea mineral resources possess vast reserves; yet, the depositional environment is extremely harsh, and the mining challenges are significant. Overcoming the technical hurdles of deep-sea mining and protecting the marine environment to achieve sustainable development and utilization of seabed resources are major challenges in the field of marine resource development. In this work, we employ a coupled Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) approach with the objective of enhancing the collection efficiency of deep-sea polymetallic nodules. The research focuses on adjusting and optimizing the collection parameters of a dual-jet collector. We examine the influence of the collector's jet angle and velocity on the collection efficiency. We conduct a numerical analysis of the movement characteristics of nodules, the distribution of the flow field, and the efficiency of nodule collection. The results indicate that when the rear jet angle is too small, the stripping and blocking effects on the nodules deteriorate. Conversely, when the jet angle is too large, the upwelling flow velocity decreases. The optimal collection effect is achieved with a rear jet angle of 55°. Lower jet velocities result in poorer nodule stripping, collection, and lifting. Higher jet velocities, however, increase seafloor disturbance and reduce the device's energy utilization efficiency. The collection efficiency is optimal at jet velocities ranging from 8 to 9 m/s. This research provides valuable insights for the design of high-efficiency dual-jet collector devices.

The red or orange emitters based on phenylquinoline or trifluoromethylpyridine iridium complexes with dimesitylboryl or diphenylphosphoryl fluorenyl unit

Novel complexes bis[2-(4-(7-dimesitylboryl-9,9-diethylfluoren-2-yl)phenyl)-4-phenyl- quinolyl-C2, N] iridium (acetylacetonate or 2-picolinic acid), bis[2-[4-(7-diphen- ylphosphoryl-9,9-diethylfluoren-2-yl)phenyl)-4-phenylquinolyl-C2, N]iridium (acetyl-acetonate or 2-picolinic acid), and bis[2-(7-dimesitylboryl-9, 9′-diethylfluoren-2-yl)-5-trifluoromethylpyridinto-C3, N] iridium (acetylacetonate or 2-picolinic acid) were synthesized. 7-Dimesitylboryl (DMB) or 7-diphenylphosphoryl (DPPO) 9,9-diethylfluorenyl with larger steric hindrance was introduced into 2-phenyl-4-phenylquinoline or 5-trifluoromethylpyridine iridium complex to improve the electron-injection and electron-transport abilities and to decrease intermolecular interaction, which promoted luminous efficiency and adjusted emission. The devices displayed stable electroluminescent (EL) peaks at about 620, 600 and 584 nm, which exhibited approximate CIE coordinates of (0.67, 0.33), (0.62, 0.38) and (0.58, 0.42) with maximum current (external quantum) efficiencies of 9.1 (5.7 %), 13.2 (8.7 %) and 6.4 cd/A (3.5 %). Slow decay and high efficiency of devices showed the potential red or orange emitters.

Chemically anchored black phosphorus/chromophore composite luminescent materials towards solid-state photoluminescence and electroluminescence

As a promising two-dimensional (2D) material, black phosphorus (BP) has gained great attention because of its intrinsic physicochemical characteristics. However, BP is easy to be oxidized and form various surface defects, which decreases the charge transport and makes luminescence difficult. Herein, we report a facile strategy to synthesize chemically anchored BP/chromophore composite luminescent materials by integrating 2D BP nanosheets with boron dipyrromethene (BODIPY) dyes through simple sonication reactions. Solids of BP composite materials are brightly fluorescent with 5 orders of magnitude increase of photoluminescence intensity compared with the pure solids of BP and BODIPY. 2D BP nanosheets with large specific surface area and lone pair electrons facilitate chemisorption of BODIPY by forming covalent interactions between P and B/N atoms, which not only passivates the surface of BP and eliminates the oxidation, but also prevents the aggregation caused quenching (ACQ) issue of BODIPY. Furtherly, the organic light-emitting diodes (OLEDs) based on the BP/chromophore composite luminescent materials were first successfully achieved, the electroluminescence spectra of which cover the full spectrum of red, green, and blue visible light. This work provides a brand-new approach to further design and development of high mobility and high luminous efficiency composite luminescent materials and devices based on BP.

Tailoring CoAl2O4 inversion degree-driven photocarrier separation and injection for photoelectrochemical water splitting

Highly efficient photoanodes are highly desirable for hydrogen production to construct photoelectrochemical (PEC) water oxidation devices. This work used the spinel-structured CoAl2O4 (CAO) as the cocatalysts to BiVO4(BVO), delivering the high photocurrent density of 3.85 mA/cm2 at 1.23 VRHE. Interestingly, their PEC performance depended on the CAO's inversion degree (δ). When δ = 0.2, the oxygen evolution process on CAO can cooperatively adsorb *OOH and dissociate the O2, then the *OH absorbs on the re-exposed active site again, leading to an improved charge separation on the surface. Meanwhile, the n-p heterojunction was formed at the interface of BVO/CAO, with the most robust built-in field strength at δ = 0.2, and the charge separation in bulk was greatly improved. Additionally, the CAO can also retard the photo corrosion of BVO by effectively extract and reservoir the photoholes, achieving over 10 h of long-term durability on BVO/CAO-450. This work illustrates the roles of CAO, clarifies the effect of inversion degree on PEC water oxidation, offers fresh insights into constructing highly efficient and stable OER catalysts, and provides fundamentals for developing high-efficiency PEC devices.

Interacting Emission Species among Donor and Acceptor Moieties in a Donor-Grafted Polymer Host/TADF-Guest System and Their Effects on Photoluminescence and Electroluminescence.

Thermally activated delayed fluorescence (TADF)-based electroluminescence (EL) devices adopting a host/guest strategy in their emitting layer (EML) are capable of realizing high efficiency. However, TADF emitters composed of donor and acceptor moieties as guests dispersed in organic host materials containing a donor and/or an acceptor are subject to donor-acceptor (D-A) interactions. In addition, electron delocalization between neighboring emitter molecules could form different species of aggregates. Here, we investigate the effects of intermolecular interacting emission species on the optoelectronic properties of sky-blue/green/red (sB/G/R) TADF emitters as guests using poly(biphenyl-Si/Ge) grafted with various donor moieties as hosts. We found the presence of guest/guest exciplex (Dg/Ag)*, host/guest exciplexes (Dh/Ag)*, and aggregates through the exploration of interactions between neighboring TADF guest molecules and between host and TADF-guest molecules. The nonradiative 3(Dh/Ag)* (ΔEST ≈ 0.5 eV) could increase the internal conversion rate (kIC) and reduce delayed luminescence, and both of them could cause a decrease in PLQY. The luminescence of 3(Dh/Ag)* may have a positive or negative effect on PLQY depending on its triplet energy. As the singlet and triplet energies of (aggregate)* are lower than those of (ICT)*, energy transfer from (ICT)* to (aggregate)* could occur. The low PLQY nature of (aggregate)* means that it is more likely to cause quenching in device emission. The emissions from (Dh/Ag)* and (aggregate)* are found to have increased full width at half-maximum and lead to lower emission color purity. Such intermolecular interactions should also occur in host/guest (TADF) systems and nondoped TADF emitter systems and thus are important factors for the molecular design of the TADF emitter and/or its accompanying host for high device efficiency and emission color purity.

Shortwave-Infrared Silver Chalcogenide Quantum Dots for Optoelectronic Devices.

Silver chalcogenide (Ag2X, X = S, Se, Te) semiconductor quantum dots (QDs) have been extensively studied owing to their short-wave infrared (SWIR, 900-2500 nm) excitation and emission along with lower solubility product constant and environmentally benign nature. However, their unsatisfactory photoluminescence quantum yields (PLQYs) make it difficult to obtain optoelectronic devices with high performances. To tackle this challenge, researchers have made great efforts to develop valid strategies to improve the PLQYs of SWIR Ag2X QDs by suppressing their nonradiative recombination of excitons. In this Perspective, we summarize the significant approaches of heteroatom doping and surface passivation to enhance the PLQYs of SWIR Ag2X QDs, and we conclude their application in high-efficiency optoelectronic devices. Finally, we examine the future trends and promising opportunities of Ag2X QDs with regard to their optical properties and optoelectronics. We believe that this Perspective will serve as a valuable reference for future advancement in the synthesis and application of SWIR Ag2X QDs.

Next-Generation Self-Powered Photodetectors using 2D Bismuth Oxide Selenide Crystals.

The concept of self-powered photodetectors has attracted significant attention due to their versatile applications in areas such as intelligent systems and hazardous substance detection. Among these, p-n junction and Schottky junction photodetectors are the most widely studied types; however, their fabrication processes are often complex and costly. To overcome these challenges, we focused on the emerging self-powered, ultrasensitive photodetector platform based on photoelectrochemical (PEC) principles. This platform leverages the unique properties of the emerging material bismuth oxide selenide (Bi2O2Se), which features a wide bandgap (∼2 eV) and a high absorption coefficient. We utilized chemical exfoliation to obtain thin layers of Bi2O2Se, enabling highly efficient photodetection. The device characterization demonstrated impressive performance metrics, including a responsivity of 97.1 μA W-1 and a specific detectivity of 2 × 108 cm Hz 1/2 W-1. The PEC photodetector also exhibits broad-spectrum sensitivity, from blue to infrared wavelengths, and features an ultrafast response time of ∼82 ms and a recovery time of ∼86 ms, highlighting its practical potential. Moreover, these self-powered photodetectors show excellent stability in electrochemical environments, positioning them promising candidates for integration into future high-efficiency devices.

Surface plasmon-mediated photoluminescence boost in graphene-covered CsPbBr3 quantum dots

The optical properties of graphene (Gr)-covered CsPbBr3 quantum dots (QDs) were investigated using micro-photoluminescence spectroscopy, revealing a remarkable three orders of magnitude enhancement in photoluminescence (PL) intensity compared to bare CsPbBr3 QDs. To elucidate the underlying mechanisms, we combined experimental techniques with density functional theory (DFT) calculations. DFT simulations showed that the graphene layer generates interfacial electrostatic potential barriers when in contact with the CsPbBr3 surface, impeding carrier leakage from perovskite to graphene and enhancing radiative recombination. Additionally, graphene passivates CsPbBr3 surface defect states, suppressing nonradiative recombination of photo-generated carriers. Our study also revealed that graphene becomes n-doped upon contact with CsPbBr3 QDs, activating its plasmon mode. This mode resonantly couples with photo-generated excitons in the perovskite. The momentum mismatch between graphene plasmons and free-space photons is resolved through plasmon scattering at Gr/CsPbBr3 interface corrugations, facilitating the observed super-bright emission. These findings highlight the critical role of graphene as a top contact in dramatically enhancing CsPbBr3 QDs’ PL. Our work advances the understanding of graphene-perovskite interfaces and opens new avenues for designing high-efficiency optoelectronic devices. The multifaceted enhancement mechanisms uncovered provide valuable insights for future research in nanophotonics and materials science, potentially leading to breakthroughs in light-emitting technologies.