- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Carrier Transport Mechanisms Underlying the Bidirectional VTH Shift in p-GaN Gate HEMTs Under Forward Gate Stress
摘要： The threshold voltage (VTH) instability of p-GaN/AlGaN/GaN HEMTs was investigated under forward gate stress. A unique bidirectional VTH shift (ΔVTH) with the critical gate voltage (VG) of 6 V was observed. The carrier transport mechanisms underlying the ΔVTH were extensively investigated through the voltage-dependent, time-resolved, and temperature-dependent gate current. The gate current is decomposed into electron and hole current in three distinct regions with respect to VG, which are off-state for VG < 1.2 V (VTH), on-state for 1.2 V < VG < 5 V and “gate-injected” region for VG > 5 V. In off-state, the electrons were thermally activated and transport towards the gate, while electron-trapping governed by the space charge limited conduction (SCLC) in AlGaN barrier was observed in on-state and “gate-injected” region. Such an electron-trapping effect results in the positive VTH shift for VG < 6 V. Meanwhile, the marginal hole transport from gate by thermal activation was also captured by gate current, which features negligible impact on VTH. However, for VG > 6 V, a drastic hole injection triggered by high VG takes place that causes subsequent hole-trapping in AlGaN barrier and hole-injection into GaN buffer. The injected holes enhance the positive charge in the gate region and turned the positively shifted VTH into a negative shift.
关键词： hole injection,threshold voltage shift,p-GaN HEMT,electron trapping,carrier transport mechanisms,gate stress
更新于2025-09-23 15:22:29
-
Sub-50 picosecond to microsecond carrier transport dynamics in pentacene thin films
摘要： Carrier transport dynamics from sub-50 ps to (cid:2)ls over five temporal decades in pentacene films was studied by transient photoconductivity. The behavior of the temperature independent photocurrent peak suggests that the photogenerated carriers exhibit pre-trapping transport in extended states upon pulsed laser excitation. From 300 ps to (cid:2)30 ns, the carriers thermalize and fall into shallow band tail states, and multiple-trapping and release transport dominates. From (cid:2)30 ns to (cid:2)ls, the weak temperature dependence of power-law photocurrent decay and the linear relation of logarithmic photocurrent with T(cid:3)1/4 suggest a variable range hopping transport in deep trap states.
关键词： transient photoconductivity,carrier transport dynamics,pentacene thin films,multiple-trapping and release transport,variable range hopping transport
更新于2025-09-23 15:21:21
-
Role of CdSe and CdSe@ZnS quantum dots interlayers conjugated in inverted polymer solar cells
摘要： We demonstrate the use of CdSe quantum dots (QDs) as an interlayer for improving photovoltaic performance in the inverted polymer solar cells (iPSCs). The conjugation of CdSe and CdSe@ZnS core@shell QDs between polyethylenimine ethoxylated (PEIE) polymer and PTB7:PC71BM blended layer played an important role in increasing the short circuit current density by F€orster resonance energy transfer (FRET) and efficient charge transport. The drastic mutual photoluminescence quenching suggests that the photon energy absorbed by PTB7:PC71BM are effectively transferred to the QDs. The PTB7:PC71BM based iPSCs with the CdSe QDs interlayer exhibits higher power conversion efficiency of 8.13%, which is 13.4% higher than that of the control device. The iPSCs with CdSe@ZnS QDs interlayer showed relatively lower PCE of 7.31%, which could be due to an increase in carrier recombination inside QDs by relatively high energy level of ZnS shell. As a consequence, the enhanced photovoltaic performance of iPSCs with CdSe QDs interlayer can be attributed to an effective charge transport and an increase in the overall photocurrent by FRET.
关键词： Carrier transport,Resonance energy transfer,Quantum dots,Inverted polymer solar cells,CdSe,Energy level alignment
更新于2025-09-23 15:21:01
-
Efficient Defect Passivation of Sb <sub/>2</sub> Se <sub/>3</sub> Film by Tellurium Doping for High Performance Solar Cells
摘要： Defect in a semiconductor dictates carrier transport and recombination, which is one of the critical factors that influences the power conversion efficiency in solar cells. In this study, we demonstrate that the introduction of tellurium is able to fine tune the atomic ratio of Se/Sb in Sb2Se3 thin film, both Se-rich and Sb-rich Sb2Se3 are well obtained. On the ground of device fabrication and deep level defect spectroscopy characterization, we experimentally disclose that Se-rich Sb2Se3 favors the formation of SeSb and VSb defects, while Sb-rich condition benefits the formation of SbSe and VSe defects. With appropriately excess Se in Sb2Se3, a net efficiency improvement of 2% is obtained when compared with the pristine Sb2Se3 based solar cells. Our study provides an effective strategy to manipulate the defect formation in Sb2Se3 solar cell and inspires further improvement in the efficiency of Sb2Se3 solar cells.
关键词： Sb2Se3,defect passivation,tellurium doping,solar cells,carrier transport
更新于2025-09-23 15:19:57
-
Highly efficient bifacial CsPbIBr <sub/>2</sub> solar cells with a TeO <sub/>2</sub> /Ag transparent electrode and unsymmetrical carrier transport behavior
摘要： Bright red CsPbIBr2 films possess intrinsic semitransparent features, which make them promising materials for smart photovoltaic windows, power plants, curtain walls, top cells for tandem solar cells, and bifacial photovoltaics. In this work, bifacial CsPbIBr2 perovskite solar cells (PSCs) have been fabricated by adopting an ultrathin silver (Ag) film transparent anode and a tellurium oxide (TeO2) optical modifying layer. The results showed that the transmittance of the TeO2 (40 nm)/Ag (11 nm) transparent top anode matched well with the light absorption range of the CsPbIBr2 film, and the resulting bifacial PSCs exhibited PCEs of 8.04% and 5.32% when illuminated from the FTO and Ag sides, respectively. By introducing cesium iodide-treated CsPbIBr2 layers, the PSCs achieved superior PCEs of 8.46% (FTO side) and 6.40% (Ag side) with a bifacial factor of 75.65%, which is the best performance of bifacial CsPbIBr2 PSCs reported to date. Interestingly, an identical cell showed a significantly higher fill factor, more efficient carrier transport, and better efficiency and stability when illuminated from the Ag side than from the FTO side, a phenomenon strongly related to the parasitic absorption of the spiro-OMeTAD layer below 420 nm. Consequently, we have found a route similar to “shooting fish in a barrel” to enhance the carrier transport, suppress the carrier recombination, and improve the stability of bifacial semitransparent CsPbIBr2 PSCs: turning the Ag side towards the sun.
关键词： unsymmetrical carrier transport behavior,perovskite solar cells,TeO2/Ag transparent electrode,bifacial CsPbIBr2 solar cells,semitransparent photovoltaics
更新于2025-09-23 15:19:57
-
Evaluating the performance of InGaN/GaN multi-quantum-well solar cells operated at elevated temperatures via DC and small-signal AC analysis
摘要： InGaN/GaN multi-quantum-well (MQW) solar cells are investigated with temperature-dependent DC and AC analysis, and the effects of differing QW number and thickness are determined. The carrier transport is shown to be dominated by thermionic emission rather than tunneling at elevated temperature but limited by recombination outside the depletion region. Temperature-dependent AC parameters of the III-N MQW devices in high-level injection are determined through a refined AC circuit model of the device. It is shown that the use of AC small-signal analysis and its ability to extract stored charge in the QWs, the comparison of built-in potential to VOC, and other solar cell critical values allows a device designer insight not possible via DC analysis alone. This critical data suggests that the number of QWs and total depletion volume needs to be matched to the operational temperature of a given high temperature solar cell.
关键词： AC circuit model,multi-quantum-well,solar cells,recombination,VOC,DC and AC analysis,depletion region,built-in potential,InGaN/GaN,thermionic emission,carrier transport,temperature-dependent
更新于2025-09-19 17:13:59
-
Enhanced carrier mobility and power conversion efficiency of organic solar cells by adding 2D Bi<sub>2</sub>OS<sub>2</sub>
摘要： Although polymer solar cells (PSCs) have many advantages, they have obtained great progress in the two decades, the low charge carrier mobility still restricts performance progress of PSCs. Two-dimensional (2D) Bi-based semiconductor nanomaterial (Bi2OS2) can be a potential material for improving the charge carrier mobility in the active layer of PSCs, because it exhibits a high carrier mobility, suitable band gap, wide absorption range, and good stability. In this work, we synthesize the 2D Bi2OS2 nanomaterial and incorporate it into active layer of PSCs as a third component for the first time. By introduction 1 wt% 2D Bi2OS2 nanomaterial into the PSCs, the power conversion efficiency (PCE) of PSCs can be obviously improved by more than 17% comparison with binary PSCs (from 10.51% to 12.31%). The enhancement of PCE is mainly due to the improving of charge transport, surface morphology, and crystallization of active layer. It is worth noting that the 2D Bi2OS2 play the role of the heterogeneous nucleation in the active layer, resulting in the enhanced crystallization of PBDB-T and ITIC. These results not only provide a way to improve the performance of PSCs, but also show that the 2D Bi2OS2 nanomaterial has great potential application in the PSCs.
关键词： crystallinity,2D Bi2OS2 nanomaterial,Polymer solar cells,charge carrier transport
更新于2025-09-16 10:30:52
-
Development of InP Quantum Dot-based Light Emitting Diodes
摘要： High performance quantum dot light emitting diode (QLED) is being considered as the next generation technology for energy efficient solid-state lighting and displays. InP QLED is the most promising alternative of the toxic CdSe QLED. Unlike the problems of poor hole injection in CdSe-based QLED, highly delocalized electrons and parasitic emissions are serious problems in green-emitting InP QLED. The loss mechanism and device physics in InP QLED have not been sufficiently studied since the first report of InP QLED in 2011. This review summarized the recent efforts on improving the performance of InP QLED, from the perspectives of core/shell structures to optimization of carrier transport layers. It is our intention to conduct a review as well as clarify some previous misunderstandings on the device physics in InP QLED, and provide some insights for the possible solutions of the challenging problems in InP QLED.
关键词： InP quantum dots,carrier transport layers,parasitic emissions,core/shell structures,QLED
更新于2025-09-16 10:30:52
-
SnO2 surface defects tuned by (NH4)2S for high-efficiency perovskite solar cells
摘要： Tin oxide (SnO2) is widely adopted as an electron transport layer (ETL) in perovskite solar cells (PSCs). However, the oxygen vacancies of the SnO2 not only are the trap states of the nonradiative recombination of photo-generated carriers, but also build the potential barrier of carrier transport. To solve this issue, ammonium sulfide [(NH4)2S] is introduced to the SnO2 precursor for passivating the surface defects by terminating the Sn dangling bonds (S–Sn bonds). After reducing the surface traps, the electron mobility and conductivity of SnO2 film are enhanced significantly while the carrier recombination is decreased. Additionally, the energy level of S-SnO2 is also slightly modified. Therefore, this sulfide-passivated mothed remarkably improves the electron collection efficiency of the ETL. Furthermore, the linkage of Sn–S–Pb anchors the perovskite crystals at the perovskite/SnO2 interface, which increases the electron extraction efficiency and the stability of PSC. Based on this S-SnO2 ETL, the power conversion efficiency of the PSC is greatly promoted from 18.67% to 20.03%, compared with the reference one. In this study, it is proven that the surface defect passivation of SnO2 is an efficient and simple method to improve the photovoltaic performance, as a promising ETL for high-efficiency device.
关键词： Oxygen vacancy,Carrier transport dynamic,SnO2 electron transport layer,Surface passivation,Perovskite solar cells
更新于2025-09-12 10:27:22
-
The Impact of Mobile Ions on the Steady State Performance of Perovskite Solar Cells
摘要： Mobile ions in perovskite solar cells induce many unique transient phenomena, while their influence under steady-state, the primary operating condition, has received little attention. Therefore, in this work we employ ionic-drift diffusion models to assess how the steady-state distribution of mobile ions affects the photogenerated carrier collection, and their redistribution due to dopants and energy band alignment. We demonstrate that mobile ions can transform the carrier transport mechanism from a combination of drift and diffusion to transport by diffusion only, which only impacts the device efficiency if the carrier mobility-lifetime product is limited due to increased transport losses and changed recombination dynamics. A high concentration of dopants is also required in perovskite devices for such doping to have a measurable impact while the energy alignment of the transport layers, on the other hand, can in principle result in a doping-like effect, which generally causes adverse consequences for cell efficiency.
关键词： dopants,steady-state performance,perovskite solar cells,energy band alignment,mobile ions,carrier transport
更新于2025-09-12 10:27:22