- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Enhancement of the optical gain in GaAs nanocylinders for nanophotonic applications
摘要： Semiconductor nanolasers based on microdisks, photonic crystal cavities, and metallo-dielectric nanocavities have been studied during the last few decades for on-chip light source applications. However, practical realization of low threshold, room temperature semiconductor nanolasers is still a challenge due to the large surface-to-volume ratio of the nanostructures, which results in low optical gain and hence higher lasing threshold. Furthermore, the gain in nanostructures is an important parameter for designing all-dielectric metamaterial-based active applications. Here, we investigate the impact of p-type doping, compressive strain, and surface recombination on the gain spectrum and the spatial distribution of carriers in GaAs nanocylinders. Our analysis reveals that the lasing threshold can be lowered by choosing the right doping concentration in the active III–V material combined with compressive strain. This combination of strain and p-type doping shows 100× improvement in gain and approximately five times increase in modulation bandwidth for high-speed operation.
关键词： surface recombination,optical gain,compressive strain,GaAs nanocylinders,nanophotonic applications,p-type doping
更新于2025-09-23 15:19:57
-
Delayed Fluorescence Emitter Enables Near 17% Efficiency Ternary Organic Solar Cells with Enhanced Storage Stability and Reduced Recombination Energy Loss
摘要： Charge transfer state (CT) plays an important role in exciton diffusion, dissociation, and charge recombination mechanisms. Enhancing the utilization and suppressing the recombination process of CT excitons is a promising way to improve the performance of organic solar cells (OSCs). Here, an effective method is presented via introducing a delayed fluorescence (DF) emitter 3,4-bis(4-(diphenylamino)phenyl) acenaphtho[1,2-b]pyrazine-8,9-dicarbonitrile (APDC-TPDA) in OSCs. The long-lifetime singlet excitons on APDC-TPDA can transfer to polymer donors to prolong exciton lifetime, which ensures sufficient time for diffusion and dissociation. Concurrently, the high triplet energy level (T1) of the DF material can also prevent the reverse energy transfer from CT to T1. APDC-TPDA-containing ternary OSCs shows a high PCE of 16.96% with a reduced recombination energy loss of 0.46 eV. It is noteworthy that the ternary OSC also exhibits superior storage stability. After 55 days of storage, the PCE of the ternary OSC still retains about 96% of its primitive state. Furthermore, this ternary strategy is efficient and universally applicable to OSCs, and positive results can be obtained in different systems with different DF emitters. These results indicate that the ternary strategy provides a new design idea to realize high performance OSCs.
关键词： delayed fluorescence,recombination energy loss,organic solar cells,charge transfer state,storage stabile solar cells
更新于2025-09-23 15:19:57
-
Efficient Perovskite Solar Cells by Reducing Interfacea??Mediated Recombination: a Bulky Amine Approach
摘要： The presence of non-radiative recombination at the perovskite surface/interface limits the overall efficiency of perovskite solar cells (PSCs). Surface passivation has been demonstrated as an efficient strategy to suppress such recombination in Si cells. Here, 1-naphthylmethylamine iodide (NMAI) is judiciously selected to passivate the surface of the perovskite film. In contrast to the popular phenylethylammonium iodide, NMAI post-treatment primarily leaves NMAI salt on the surface of the perovskite film. The formed NMAI layer not only efficiently decreases the defect-assisted recombination for chemical passivation, but also retards the charge accumulation of energy level mis-alignment for vacuum level bending and prevents minority carrier recombination due to the charge-blocking effect. Consequently, planar PSCs with high efficiency of 21.04% and improved long-term stability (98.9% of the initial efficiency after 3240 h) are obtained. Moreover, open-circuit voltage as high as 1.20 V is achieved at the absorption threshold of 1.61 eV, which is among the highest reported values in planar PSCs. This work provides new insights into the passivation mechanisms of organic ammonium salts and suggests future guidelines for developing improved passivation layers.
关键词： perovskite solar cells,energy level alignment,1-naphthylmethylamine iodide,non-radiative recombination,chemical passivation
更新于2025-09-23 15:19:57
-
[IEEE 2019 2nd International Conference on Power and Embedded Drive Control (ICPEDC) - Chennai, India (2019.8.21-2019.8.23)] 2019 2nd International Conference on Power and Embedded Drive Control (ICPEDC) - Efficient Electron Carrier distribution of n+ MoS <sub/>2</sub> /i-MoS <sub/>2</sub> /p-Si Heterojunction Solar Cell
摘要： In this paper, modeling and simulation study of energy harvested nano electronics of PV device and its functions under different light intensity have been discussed. The emitter layer of the proposed solar cell has been designed to enhance the photocurrent efficiency even at low electric field. The Electron-hole pair generation of the proposed model is increased to 4.9*1028 [1/ (m2*s)] due to optimized intrinsic MoS2 layer thickness. As a result, the charge carriers distribution enhanced the carrier collection efficiency in the absorber layer. This study reveals that the proposed Energy harvesting device Open-circuit Voltage(Voc) and Short circuit Current density(Jsc) are 1.982[V], 31.22[mA/cm2] respectively and its efficiency found to be 31.91 %. These simulations showed that can be environmental stability and excellent carrier distribution solar cell.
关键词： electric field,efficiency-region,charge-carrier recombination,Photogeneration,n+MoS2
更新于2025-09-23 15:19:57
-
Impact of Polymer Backbone Fluorination on the Charge Generation/Recombination Patterns and Vertical Phase Segregation in Bulk Heterojunction Organic Solar Cells
摘要： Incorporating fluorine (–F) substituents along the main-chains of polymer donors and acceptors is an effective strategy toward efficient bulk-heterojunction (BHJ) solar cells. Specifically, F-substituted polymers often exhibit planar conformations, leading to favorable packing, and electronic coupling. However, the effects of fluorine substituents on the charge generation and recombination characteristics that determine the overall efficiency of BHJ active layers remain critically important issues to examine. In this report, two PBDT[2X]T polymer analogs –poly[4,8-bis((2-ethylhexyl)oxy)benzo[1,2-b:4,5-b′]dithiophene-thiophene] [PBDT[2H]T] and its F-substituted counterpart poly[4,8-bis((2-ethylhexyl)oxy)benzo[1,2-b:4,5-b′]dithiophene-3,4-difluoro-thiophene] [PBDT[2F]T]—are studied to systematically examine how –F substituents impact the blend morphology, charge generation, carrier recombination and extraction in BHJ solar cells. Considering the large efficiency differences between PBDT[2H]T- and PBDT[2F]T-based BHJ devices, significant emphasis is given to characterizing the out-of-plane morphology of the blend films as vertical phase-separation characteristics are known to have dramatic effects on charge transport and carrier extraction in polymer-fullerene BHJ solar cells. Herein, we use electron energy loss spectroscopy (EELS) in tandem with charge transport characterization to examine PBDT[2X]T-fullerene blend films. Our analyses show that PBDT[2H]T and PBDT[2F]T possess very different charge generation, recombination and extraction characteristics, resulting from distinct aggregation, and phase-distribution within the BHJ blend films.
关键词： vertical phase segregation,bulk heterojunction,polymer backbone fluorination,organic solar cells,charge generation and recombination
更新于2025-09-23 15:19:57
-
Reducing the Singleta??Triplet Energy Gap by Enda??Group ??a???? Stacking Toward Higha??Efficiency Organic Photovoltaics
摘要： To improve the power conversion efficiencies for organic solar cells, it is necessary to enhance light absorption and reduce energy loss simultaneously. Both the lowest singlet (S1) and triplet (T1) excited states need to energetically approach the charge-transfer state to reduce the energy loss in exciton dissociation and by triplet recombination. Meanwhile, the S1 energy needs to be decreased to broaden light absorption. Therefore, it is imperative to reduce the singlet?triplet energy gap (ΔEST), particularly for the narrow-bandgap materials that determine the device T1 energy. Although maximizing intramolecular push?pull effect can drastically decrease ΔEST, it inevitably results in weak oscillator strength and light absorption. Herein, large oscillator strength (≈3) and a moderate ΔEST (0.4?0.5 eV) are found for state-of-the-art A?D?A small-molecule acceptors (ITIC, IT-4F, and Y6) owing to modest push?pull effect. Importantly, end-group π?π stacking commonly in the films can substantially decrease the S1 energy by nearly 0.1 eV, but the T1 energy is hardly changed. The obtained reduction of ΔEST is crucial to effectively suppress triplet recombination and acquire small exciton dissociation driving force. Thus, end-group π?π stacking is an effective way to achieve both small energy loss and efficient light absorption for high-efficiency organic photovoltaics.
关键词： energy loss,triplet recombination,molecular packing,nonfullerene acceptors
更新于2025-09-23 15:19:57
-
Ultrafast spectroscopic investigation of the effect of solvent additives on charge photogeneration and recombination dynamics in non-fullerene organic photovoltaic blends
摘要： The PBDB-TF:IT-4F blend is a kind of state-of-the-art non-fullerene photovoltaic blend. Herein, the effects of 1,8-diiodooctane (DIO) and 1-chloronaphthalene (CN) additives on the neat and blend film morphologies and the related ultrafast photophysical processes are studied. It is found that both DIO and CN can lead to an enhanced structural order in the in-plane direction and increased average lifetime of excitons in neat PBDB-TF films. The face-on orientation of PBDB-TF still exists in the DIO-processed PBDB-TF:IT-4F blend film, while in the case of the CN-processed blend film, molecular packing orientation is similar to that of the pristine blend film. The blend samples prepared with the two additives show increased initial exciton yields. Interestingly, in the blend samples prepared with the DIO additive, the recombination loss via the formation of polymer triplet excitons can be effectively suppressed, in comparison to the pristine and CN-processed samples. Both the DIO- and CN-processed devices show increased short-circuit current densities. The DIO-processed device is also found to have a superior fill factor due to suppressed recombination loss. The work provides a comprehensive insight into the ultrafast photophysical processes in varied blend morphologies induced by additives and their effect on the photovoltaic parameters of the devices.
关键词： charge photogeneration,ultrafast spectroscopy,recombination dynamics,solvent additives,non-fullerene photovoltaic blend
更新于2025-09-23 15:19:57
-
Experimentally Calibrated Kinetic Monte Carlo Model Reproduces Organic Solar Cell Currenta??Voltage Curve
摘要： Kinetic Monte Carlo simulations are used to describe the current-voltage characteristics of an organic bulk heterojunction solar cell. Excellent agreement between model and experiment is obtained by calibrating the injection barriers, the blend morphology and the charge transfer recombination rate with data from independent measurement techniques.
关键词： organic photovoltaics,charge recombination,Kinetic Monte Carlo simulations,morphology,charge injection
更新于2025-09-23 15:19:57
-
[IEEE 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Bengaluru, India (2018.12.17-2018.12.19)] 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Mapping of Bulk Diffusion Length and Effective Back Surface Recombination Velocity in Silicon Solar Cells
摘要： Mapping of diffusion length (L) in the bulk region and effective back surface recombination velocity (SRV) in Al-BSF and PERC Si solar cells has been carried out by utilizing the spectral response (SR) at desired wavelengths. Light beam induced current (LBIC) technique was used to generate the maps of SR and re?ectivity (R) on cell area (6”x6”). MATLAB tool was used to convert the spatial maps of SR and R into L and SRV. We found that (i) the distribution of L in multi-crystalline cells varied from grain to grain in wide range (150-600 μm) while in mono-crystalline cells, it varied in rather narrow range (450-600 μm) ; (ii) the values of SRV for PERC cells (120-250 cm/sec for mono-crystalline and 100-250 cm/sec for multi-crystalline) and Al-BSF cells (320-400 cm/sec for mono-crystalline and 250-350 cm/sec for multi-crystalline) differ by considerable magnitude due to passivation quality at back side. Three multi-crystalline Al-BSF Si solar cells of cell ef?ciencies 17.6%, 17.9% and 18.1% were investigated with the proposed methodology and demonstrated that the ef?ciency de?cit is primarily due to defects present in bulk material and poor back surface passivation.
关键词： Light beam induced current,Surface recombination velocity,Diffusion length,Si solar cells
更新于2025-09-23 15:19:57
-
Approaches to The Hagfeldt Donor and Use of Next Generation Bulky Donor Designs in Dyea??Sensitized Solar Cell Dyes
摘要： 'The Hagfeldt donor' is a bulky triarylamine building block with 4 alkyl chains in a 3-dimensional arrangement which is used with organic dyes in dye-sensitized solar cells (DSCs) in over 140 manuscripts. Many of the highest performing DSC devices in literature make use of this group due to exceptional TiO2 surface protection properties which slows recombination of electrons in TiO2 with the electrolyte. Importantly, record-setting cobalt and copper redox shuttle based-DSCs require exceptional surface protection to slow a facile recombination of electrons to these positively charged redox shuttles. Several syntheses have emerged for the Hagfeldt donor due to the need for iterative aryl-halide cross couplings complicating a straight forward route. The six synthetic strategies found in literature are described along with the challenges of each route. A recent method that has been put forward in the literature as a scalable, regioisomerically pure route is highlighted.
关键词： dye design,masked halide,dye-sensitized solar cells,low recombination functionality,Hagfeldt donor
更新于2025-09-23 15:19:57