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Wafer-Scale Fabrication of 2D PtS <sub/>2</sub> /PtSe <sub/>2</sub> Heterojunctions for Efficient and Broadband Photodetection
摘要： The fabrication of van der Waals heterostructures have mainly extends to two-dimensional materials that are exfoliated from their bulk counterparts, which is greatly limited by high-volume manufacturing. Here, we demonstrate multilayered PtS2/PtSe2 heterojunctions covering a large area on SiO2/Si substrate with a maximum size of 2" in diameter, offering throughputs that can meet the practical application demand. Theoretical simulation was carried out to understand the electronic properties of the PtS2/PtSe2 heterojunctions. Zero-bias photoresponse in the heterojunctions is observed under laser illumination of different wavelengths (405 to 2200 nm). The PtS2/PtSe2 heterojunctions exhibit broadband photoresponse, high quantum efficiency at infrared wavelengths with lower bounds for the external quantum efficiencies (EQE) being 1.2% at 1064 nm, 0.2% at 1550 nm and 0.05% at 2200 nm, and also relatively fast response time at the dozens of millisecond level. The large area, broadband 2D heterojunction photodetector demonstrated in this work further corroborating the great potential of 2D materials in the future low-energy optoelectronics.
关键词： van der Waals heterostructures,self-driving operation,quantum efficiency,broadband photodetection,photoresponsivity,wafer-scale fabrication
更新于2025-09-23 15:21:01
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A genetically encoded photosensitizer protein facilitates the rational design of a miniature photocatalytic CO2-reducing enzyme
摘要： Photosensitizers, which harness light energy to upgrade weak reductants to strong reductants, are pivotal components of the natural and artificial photosynthesis machineries. However, it has proved difficult to enhance and expand their functions through genetic engineering. Here we report a genetically encoded, 27 kDa photosensitizer protein (PSP), which facilitates the rational design of miniature photocatalytic CO2-reducing enzymes. Visible light drives PSP efficiently into a long-lived triplet excited state (PSP*), which reacts rapidly with reduced nicotinamide adenine dinucleotide to generate a super-reducing radical (PSP?), which is strong enough to reduce many CO2-reducing catalysts. We determined the three-dimensional structure of PSP? at 1.8 ? resolution by X-ray crystallography. Genetic engineering enabled the site-specific attachment of a nickel–terpyridine complex and the modular optimization of the photochemical properties of PSP, the chromophore/catalytic centre distance and the catalytic centre microenvironment, which culminated in a miniature photocatalytic CO2-reducing enzyme that has a CO2/CO conversion quantum efficiency of 2.6%.
关键词： quantum efficiency,photosensitizer protein,visible light,photocatalytic CO2-reducing enzymes,X-ray crystallography,nickel–terpyridine complex,genetic engineering
更新于2025-09-23 15:21:01
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Hybrid perovskite light emitting diodes under intense electrical excitation
摘要： Hybrid perovskite semiconductors represent a promising platform for color-tunable light emitting diodes (LEDs) and lasers; however, the behavior of these materials under the intense electrical excitation required for electrically-pumped lasing remains unexplored. Here, we investigate methylammonium lead iodide-based perovskite LEDs under short pulsed drive at current densities up to 620 A cm?2. At low current density (J < 10 A cm?2), we ?nd that the external quantum ef?ciency (EQE) depends strongly on the time-averaged history of the pulse train and show that this curiosity is associated with slow ion movement that changes the internal ?eld distribution and trap density in the device. The impact of ions is less pronounced in the high current density regime (J > 10 A cm?2), where EQE roll-off is dominated by a combination of Joule heating and charge imbalance yet shows no evidence of Auger loss, suggesting that operation at kA cm?2 current densities relevant for a laser diode should be within reach.
关键词： ion movement,electrical excitation,lasers,Auger loss,light emitting diodes,Hybrid perovskite semiconductors,Joule heating,external quantum efficiency,charge imbalance
更新于2025-09-23 15:21:01
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Pd-Pt bimetallic Nb-doped TiO2 for H2 photo-production: Gas and liquid phase processes
摘要： The performance of binary PtPd co-catalysts supported on Nb-TiO2 was tested in the gas and liquid phase photo-reforming of methanol. Co-catalyst formulations having Pt:Pd ratios from 2:1 to 1:4 were tested and the activity measured through the calculation of the quantum efficiency. Characterization of the initial and post-reaction materials showed that optimum activity is achieved in both processes by samples containing binary co-catalysts where Pd suffers an oxidation process and a PtPd alloying metallic phase is formed under reaction conditions. The analysis of catalytic output through an experimental design considering tree factors (methanol:water ratio, irradiance level, and catalyst volumetric concentration at liquid phase or surface concentration at gas phase) shows that the liquid phase process presents a rather high quantum efficiency value compared with the gas phase but the latter process displays higher atom efficiency as well as renders products with lower toxicity.
关键词： Carbon selectivity,Bimetallic co-catalyst,Quantum efficiency and yield
更新于2025-09-23 15:21:01
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Light extraction from quantum dot light emitting diodes by multiscale nanostructures
摘要： Improving the light extraction efficiency by introducing optical–functional structures outside of quantum dot light emitting diodes (QLED) for further enhancing the external quantum efficiency (EQE) is essential for its application in display and lighting industrialization. Although the efficiency of QLED has been optimized by controlling of the synthesis of the quantum dots, the low outcoupling efficiency is indeed unresolved because of total internal reflections, waveguides and metal surface absorptions within the device. Here, we are utilizing multiscale nanostructures attaching to the outer surface of the glass substrate to extract the trapped light from the emitting layers of QLED. The result indicates that both the EQE and luminance are improved from 12.29% to 17.94% and 122400 cd m-2 to 178700 cd m-2, respectively. The maximum EQE and current efficiency improve to 21.3% and 88.3 cd A?1, respectively, which are the best performance among reported green QLED with light outcoupling nanostructures. The improved performance is ascribed to eliminate total internal reflection by multiscale nanostructures attached to the outer surface of the QLED. Additionally, the simulation result of Finite-difference time domain (FDTD) also demonstrates the light trapping effect is reduced by the multiscale nanostructures. The design of the novel light outcoupling nanostructure for further improving the efficiency of QLED can promote its application in display and lighting industrializations.
关键词： quantum dot light emitting diodes,multiscale nanostructures,light extraction efficiency,external quantum efficiency,display and lighting industrialization
更新于2025-09-23 15:19:57
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Homoleptic mer-Ir(III) complexes for highly efficient solution-processable green phosphorescent organic light-emitting diodes with high current efficiency
摘要： Two new highly efficient homoleptic green-emitting meridional iridium (III) complexes namely, mer-tris[5-hexyl-8-trifluoromethyl-5H-benzo(c)(1,5)naphthyridin-6-one]iridium(III) (mer-Ir1) and mer-tris[5-ethylhexyl-8-trifluoromethyl-5H-benzo(c)(1,5)naphthyridin-6-one]iridium(III) (mer-Ir2) were designed and synthesized at high temperature. These new Ir(III) complexes consist of amide bridged trifluoromethyl substituted phenylpyridine skeleton with longer alkyl chain. Interestingly, both Ir(III) complexes, mer-Ir1 and mer-Ir2 show bright green emission (λmax = 528 nm) with high photoluminescence quantum yields of 42 and 51% in solution at room temperature, respectively. Their thermal, photophysical, electrochemical, and electroluminescent (EL) properties were fully investigated. Both complexes were used as dopants for solution-processed green phosphorescence organic light-emitting diodes (PHOLEDs). Notably, the device using mer-Ir2 as new green dopant exhibited excellent EL performance with a maximum external quantum efficiency of 20.03% and maximum current efficiency of 67.81 cd A-1. To the best of our knowledge, this is the first time, particularly Ir(C^N)3 based mer-Ir(III) isomers showing excellent EL performance with high luminous efficiency in the green region via solution-processed PHOLEDs has been reported.
关键词： high photoluminescence quantum yields,current efficiency,external quantum efficiency,homoleptic green-emitting meridional iridium (III) complexes,solution-processed green phosphorescence organic light-emitting diodes (PHOLEDs)
更新于2025-09-23 15:19:57
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Efficient Structure for InP/ZnS-Based Electroluminescence Device by Embedding the Emitters in the Electron-Dominating Interface
摘要： The charge-carrier distribution has been an important parameter in determining the efficiency of quantum-dot-based light-emitting diodes (QLEDs). In this Letter, we demonstrate a new inverted device structure of ITO/ZnO/polyethylenimine/quantum dots (QDs)/1,3,5-tris(N-phenylbenzimidazole-2-yl)benzene (TPBi)/4,4′-bis(9-carbazolyl)-2,2′-biphenyl (CBP)/MoO3/Al for improving the efficiency of InP-QD-based QLEDs. By introducing a thin layer of electron transport materials, the hole accumulation at the hole transport layer and the QD interface is largely reduced, which suppresses the quenching effect of holes on the QD emission. Compared with the conventional device structure with the emitters at ZnO/CBP pn junction, the peak current efficiency (external quantum efficiency) increases from 3.83 (5.17 cd/A) to 6.32% (8.54 cd/A) by imbedding the QDs at the electron-dominating interface of ZnO/TPBi. The analysis reveals that an internal quantum efficiency of nearly 100% is achieved for the InP-QD-based device (with a photoluminescence quantum yield of 32%). This work provides an alternative device structure for achieving high-efficiency QLED devices.
关键词： electron transport materials,quantum-dot-based light-emitting diodes,internal quantum efficiency,charge-carrier distribution,InP-QD-based QLEDs
更新于2025-09-23 15:19:57
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High External Quantum Efficiency in Fluorescent OLED by Cascade Singlet Harvesting Mechanism
摘要： The cascade singlet harvesting (CSH) organic light-emitting diodes (OLEDs) are devised to resolve the low quantum efficiency issue of fluorescent OLEDs by efficient singlet exciton harvesting of the fluorescent emitters. The CSH mechanism is realized by doping a fluorescent emitter in the singlet exciton harvesting matrix consisted of high energy exciplex and low energy exciplex. The high energy exciplex serves as the main component of the emitting layer and the low energy exciplex is a medium harvesting the singlet excitons of the fluorescent emitter. Both exciplexes are thermally activated delayed fluorescence type exciplexes to effectively harvest singlet excitons by reverse intersystem crossing process. The singlet excitons of the low energy exciplex are harvested by the high energy exciplex through F?rster energy transfer and then the singlet excitons of the fluorescent emitter are harvested by the low energy exciplex through the second F?rster energy transfer process. The CSH mechanism maximizes the singlet exciton formation in the fluorescent emitter, which significantly enhances the external quantum efficiency (EQE) of the fluorescent OLEDs. The optimization of the emitting layer structure provides high EQE of 19.9% in the fluorescent OLEDs compared with 10.4% of a conventional singlet harvesting fluorescent OLED.
关键词： energy transfer,external quantum efficiency,fluorescent OLEDs,thermally activated delayed fluorescence,cascade singlet harvesting,exciplex
更新于2025-09-23 15:19:57
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A Biomimetic-Computational Approach to Optimizing the Quantum Efficiency of Photovoltaics
摘要： The most advanced low-cost organic photovoltaic cells have a quantum efficiency of ~10%. This is in stark contrast to plant/bacterial light-harvesting systems which offer quantum efficiencies close to unity. Of particular interest is the highly effective quantum coherence-enabled energy transfer. Noting that quantum coherence is promoted by charged residues and local dielectrics, classical atomistic simulations and Time-Dependent Density Functional Theory (TD-DFT) can be used to identify charge/dielectric patterns and electronic coupling at exactly defined energy transfer interfaces incorporating structural information obtained on photosynthetic protein-pigment complexes. To this end, the project focuses on the first protein-pigment-redox carrier complex of the linear electron transport phosphorylation chain termed photosystem II [PSII]. PSII contains more than 10 major polypeptides in addition to hundreds of pigment molecules amounting to a molecular mass in excess of 1 Mio Dalton. Owing to the complexity and fragility of PSII, this project bases the overall architecture of PSII on in situ EM data providing structural clues about the entire, unperturbed PSII complex. Albeit not to high resolution when compared to X-ray crystallography and NMR spectroscopy, the EM tomographic results and projection maps provide an accurate delineation of the native complex suitable for fitting high-resolution X-ray data of PSII subcomplexes towards an atomistic model of the entire PSII complex. This must also include the light-harvesting antennae, i.e. the light-harvesting chlorophyll (Chl) a/b protein complex [LHCII]. With respect to LHCII one should take into account positioning LHCII next to PSII as well as in a separate, complementary membrane thus permitting to test for both, horizontal (intramembrane) and vertical (intermembrane) energy transfer, respectively. The presence of LHCII in a membrane different from PSII is supported by strong biochemical evidence and tomographic data, and it has also been noted that the organization of LHCII may change in response to environmental conditions.
关键词： photosystem II,biomimetic,computational approach,quantum efficiency,light-harvesting chlorophyll,photovoltaics
更新于2025-09-23 15:19:57
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Utility of copper oxide nanoparticles (CuO-NPs) as efficient electron donor material in bulk-heterojunction solar cells with enhanced power conversion efficiency
摘要： In the present work, we have endeavored the utilization of wet-chemically synthesized copper oxide nanoparticles (CuO-NPs) as the active layer in hybrid bulk heterojunction (BHJ) solar cells. The BHJs with CuO-NPs display significantly different physics from customary BHJs, and prove a noteworthy improvement in their performance. It is noted that with the addition of CuO-NPs, the morphology of the photoactive layer endures significant changes. Incorporating CuO-NPs is an additional paradigm for BHJs solar cells which enhances the photocurrent density from 9.43 mA/cm2 to 11.32 mA/cm2 and the external quantum efficiency as well. Also the power-conversion efficiency (PCE) improved from 2.85 % to 3.82 % without harming the open circuit voltage and the fill factor. The enhancement in PCE achieved here makes it worthy to design high-performance organic solar cells holding inorganic nanoparticles.
关键词： thin films,Bulk heterojunction,Solar cells,external quantum efficiency,Copper oxide nanoparticles,photo current density
更新于2025-09-23 15:19:57