High performance wide bandgap perovskite solar cell with low V_(OC) deficit less than 0.4 V

Wide bandgap perovskite solar cells(PSCs)have attracted significant attention because they can be applied to the top cells of tandem solar cells.However,high open-circuit voltage(V_(OC))deficit(>0.4 V)result from poor crystallization and high non-radiative recombination losses become a serious limitation in the pursuit of high performance.Here,the relevance between different Pbl_(2)proportions and performance parameters are revealed through analysis of surface morphology,residual stress,and photostability.The increase of Pbl_(2)proportion promotes crystal growth and reduces the work function of the perovskite film surface and promotes the energy level alignment with the carrier transport layer,which decreased the V_(OC)deficit.However,residual PbI_(2)exacerbated the stress level of perovskite film,and the resulting lattice disorder deteriorated the photostability of the device.Ultimately,after the synergistic passivation of residual PbI_(2)and PEAI,the V_(OC)achieves 1.266 V and V_(OC)deficit is less than 0.4 V,the record value in wide bandgap PSCs.

Alkyl chain modulation of asymmetric hexacyclic fused acceptor synergistically with wide bandgap third component for high efficiency ternary organic solar cells

Herein,two asymmetric hexacyclic fused small molecule acceptors(SMAs),namely BP4F-HU and BP4F-UU,were synthesized.The elongated outside chains in the BP4F-UU molecule played a crucial role in optimizing the morphology of blend film,thereby improving charge mobility and reducing energy loss within the corresponding film.Notably,the PM6:BP4F-UU device exhibited a higher open-circuit voltage(V_(oc))of 0.878 V compared to the PM6:BP4F-HU device with a V_(oc)of 0.863 V.Further,a new wide bandgap SMA named BTP-TA was designed and synthesized as the third component to the PM6:BP4F-UU host binary devices,which showed an ideal complementary absorption spectrum in PM6:BP4F-UU system.In addition,BTP-TA can achieve efficient intermolecular energy transfer to BP4F-UU by fluorescence resonance energy transfer(FRET)pathway,due to the good overlap between the photoluminescence(PL)spectrum of BTP-TA and the absorption region of BP4F-UU.Consequently,ternary devices with 15wt%BTP-TA exhibits broader photon utilization,optimal blend morphology,and reduced charge recombination compared to the corresponding binary devices.Consequently,PM6:BP4F-UU:BTP-TA ternary device achieved an optimal power conversion efficiency(PCE)of 17.83%with simultaneously increased V_(oc)of 0.905 V,short-circuit current density(J_(sc))of 26.14 mA/cm^(2),and fill factor(FF)of 75.38%.

The Advent of Wide Bandgap Green-Synthesized Copper Zinc Tin Sulfide Nanoparticles for Applications in Optical and Electronic Devices

Power-electronic devices are widely used in various applications, such as voltage and frequency control for transmitting and converting electric power. As these devices are becoming increasingly important, there is a need to reduce their losses and improve their performance to reduce electric power consumption. Current power semiconductor devices, such as inverters, are made of silicon (Si), but the performance of these Si power devices is reaching its limit due to physical properties and energy bandgap. To address this issue, recent developments in wide bandgap (WBG) semiconductor materials, such as silicon carbide (SiC) and gallium nitride (GaN), offer the potential for a new generation of power semiconductor devices that can perform significantly better than silicon-based devices. In this research, a green synthesized copper-zinc-tin-sulfide (CZTS) nanoparticle is proposed as a new WBG semiconductor material that could be used for optical and electronic devices. Its synthesis, consisting of the production methods and materials used, is discussed. The characterization is also discussed, and further research is recommended in the later sections to enable the continual advancement of this technology.

Stability of mixed-halide wide bandgap perovskite solar cells: Strategies and progress

Benefiting from the superior optoelectronic properties and low-cost manufacturing techniques,mixedhalide wide bandgap(WBG)perovskite solar cells(PSCs)are currently considered as ideal top cells for fabricating multi-junction or tandem solar cells,which are designed to beyond the Shockley-Queisser(S-Q)limit of single-junction solar cells.However,the poor long-term operational stability of WBG PSCs limits their further employment and hinders the marketization of multi-junction or tandem solar cells.In this review,recent progresses on improving environmental stability of mixed-halide WBG PSCs through different strategies,including compositional engineering,additive engineering,interface engineering,and other strategies,are summarized.Then,the outlook and potential direction are discussed and explored to promote the further development of WBG PSCs and their applications in multijunction or tandem solar cells.

Blue-Light Emission from Undoped and Rare Earth-Doped Wide Bandgap Oxides

Rare earth-doped oxide thin-film phosphors may emerge as an alternate choice for the blue phosphor, due to their chemical and thermal stability in high vacuum and absence of corrosive gas emission under electron bombardment. The blue phosphors in this study were activated in air at temperatures suitable for glass substrates, which have been used in a number of applications. The effects of rare earth ions and oxide hosts on the blue-light-emitting properties of phosphors are discussed. In addition, novel blue-light emission was observed in certain typical undoped wide bandgap oxides. The luminescence of the oxides depends on the growth and annealing conditions under different atmospheres, suggesting that it is associated with the presence of oxygen vacancies. Radiative processes related to oxygen vacancies were also presented.

Electron Cyclotron Resonance Deposition of Wide Bandgap a-SiC:H Films Using Acetylene under High Hydrogen Dilution

The deposition of hydrogenated amorphous silicon carbide (a-SiC.H) films from a mixture of silane, acetylene and hydrogen gas using the electron cyclotron resonance chemical vapour deposition (ECR-CVD) process is reported. The variation of the deposition and film characteristics such as the deposition rate- optical bandgap, photoluminescence and the infra-red (IR) absorption as a function of the hydrogen dilution is investigated. The deposition rate increases to a maximum value of ~25 nm/min at a moderate hydrogen diIution ratio of ~20 [hydrogenflow (sccm)/acetylene+silane flow (sccm)], and decreases in response to a further increase in the hydrogen dilution. There is no strong dependence of the optical bandgap on the hydrogen dilution within the dilution range investigated (10 to 60), and the optical bandgap calculated from the E04 method varied marginally from ~2.85 eV to ~3.17 eV. The room temperaturephotoluminescence (PL) peak energy and intensity shows a prominent shift to a maximum value of ~2.17 eV corresponding to maximum PL intensity at a moderate hydrogen diIution of ~30.The PL intensity shows a strong dependence on the hydrogen dilution variation. IR absorption results show that films deposited at higher hydrogen dilution have more Si-C bonding.

Progress of power field effect transistor based on ultra-wide bandgap Ga_2O_3 semiconductor material

As a promising ultra-wide bandgap semiconductor, gallium oxide(Ga_2O_3) has attracted increasing attention in recent years. The high theoretical breakdown electrical field(8 MV/cm), ultra-wide bandgap(～ 4.8 eV) and large Baliga's figure of merit(BFOM) of Ga_2O_3 make it a potential candidate material for next generation high-power electronics, including diode and field effect transistor(FET). In this paper, we introduce the basic physical properties of Ga_2O_3 single crystal, and review the recent research process of Ga_2O_3 based field effect transistors. Furthermore, various structures of FETs have been summarized and compared, and the potential of Ga_2O_3 is preliminary revealed. Finally, the prospect of the Ga_2O_3 based FET for power electronics application is analyzed.

Surface-functionalized hole-selective monolayer for high efficiency single-junction wide-bandgap and monolithic tandem perovskite solar cells

Carbazole moiety-based 2PACz([2-(9H-carbazol-9-yl)ethyl]phosphonic acid)self-assembled monolayers(SAMs)are excellent hole-selective contact(HSC)materials with abilities to excel the charge-transferdynamics of perovskite solar cells(PSCs).Herein,we report a facile but powerful method to functionalize the surface of 2PACz-SAM,by which reproducible,highly stable,high-efficiency wide-bandgap PSCs can be obtained.The 2PACz surface treatment with various donor number solvents improves assembly of 2PACz-SAM and leave residual surface-bound solvent molecules on 2PACz-SAM,which increases perovskite grain size,retards halide segregation,and accelerates hole extraction.The surface functionalization achieves a high power conversion efficiency(PCE)of 17.62%for a single-junction wide-bandgap(~1.77 e V)PSC.We also demonstrate a monolithic all-perovskite tandem solar cell using surfaceengineered HSC,showing high PCE of 24.66%with large open-circuit voltage of 2.008 V and high fillfactor of 81.45%.Our results suggest this simple approach can further improve the tandem device,when coupled with a high-performance narrow-bandgap sub-cell.

Chlorinated phthalimide polymer donor as ultra-wide bandgap and deep HOMO guest for achieving highly efficient polymer solar cells

Quaternary approach has been receiving more and more attention due to its effectiveness in improving solar cell performance, while synthesis/selection of the fourth component is yet a key issue. Herein, we report a chlorinated phthalimide based donor polymer(namely Ph I-Cl) having an ultra-wide bandgap(2.10 e V) and a deep HOMO(-5.58 e V) level. Addition of Ph I-Cl as the third component of PM6:Y6 and the fourth of PM6:Y6:PC71BM increases both hole and electron mobilities and gives rise to more balanced charge carriers mobilities. Both the short-circuit current-density and fill-factor are increased and open-circuit voltage is well maintained, delivering 17.0% and 18.1% efficiencies, respectively. These results demonstrate that chlorination on the side thiophene of phthalimide-based donor polymer is a way to make deep HOMO and ultra-wide bandgap donor polymer guest used for highly efficient ternary and quaternary strategies.

Antimony Potassium Tartrate Stabilizes Wide-Bandgap Perovskites for Inverted 4-T All-Perovskite Tandem Solar Cells with Efficiencies over 26%

Wide-bandgap(WBG)perovskites have been attracting much attention because of their immense potential as a front light-absorber for tandem solar cells.However,WBG perovskite solar cells(PSCs)generally exhibit undesired large open-circuit voltage(VOC)loss due to light-induced phase segregation and severe non-radiative recombination loss.Herein,antimony potassium tartrate(APTA)is added to perovskite precursor as a multifunctional additive that not only coordinates with unbonded lead but also inhibits the migration of halogen in perovskite,which results in suppressed non-radiative recombination,inhibited phase segregation and better band energy alignment.Therefore,a APTA auxiliary WBG PSC with a champion photoelectric conversion efficiency of 20.35%and less hysteresis is presented.They maintain 80%of their initial efficiencies under 100 mW cm^(-2)white light illumination in nitrogen after 1,000 h.Furthermore,by combining a semi-transparent WBG perovskite front cell with a narrow-bandgap tin–lead PSC,a perovskite/perovskite four-terminal tandem solar cell with an efficiency over 26%is achieved.Our work provides a feasible approach for the fabrication of efficient tandem solar cells.

Wide bandgap semiconductor-based integrated circuits

Wide-bandgap semiconductors exhibit much larger energybandgaps than traditional semiconductors such as silicon,rendering them very promising to be applied in the fields of electronics and optoelectronics.Prominent examples of semiconductors include SiC,GaN,ZnO,and diamond,which exhibitdistinctive characteristics such as elevated mobility and thermalconductivity.These characteristics facilitate the operation of awide range of devices,including energy-efficient bipolar junctiontransistors(BJTs)and metal-oxide-semiconductor field-effecttransistors(MOSFETs),as well as high-frequency high-electronmobility transistors(HEMTs)and optoelectronic components suchas light-emitting diodes(LEDs)and lasers.These semiconductorsare used in building integrated circuits(ICs)to facilitate theoperation of power electronics,computer devices,RF systems,andother optoelectronic advancements.These breakthroughs includevarious applications such as imaging,optical communication,andsensing.Among them,the field of power electronics has witnessedtremendous progress in recent years with the development of widebandgap(WBG)semiconductor devices,which is capable ofswitching large currents and voltages rapidly with low losses.However,it has been proven challenging to integrate these deviceswith silicon complementary metal oxide semiconductor(CMOS)logic circuits required for complex control functions.The monolithic integration of silicon CMOS with WBG devices increases thecomplexity of fabricating monolithically integrated smart integrated circuits(ICs).This review article proposes implementingCMOS logic directly on the WBG platform as a solution.However,achieving the CMOS functionalities with the adoption of WBGmaterials still remains a significant hurdle.This article summarizesthe research progress in the fabrication of integrated circuitsadopting various WBG materials ranging from SiC to diamond,with the goal of building future smart power ICs.

Recent Advances in Wide Bandgap Polymer Donors and Their Applications in Organic Solar Cells

Organic solar cells(OSCs)have attracted wide research interests in the past decades.In recent years,our group mainly focused on the new photovoltaic materials design and device engineering technologies for highly efficient OSCs.This account mainly summarizes our recent studies on the structural design of wide bandgap(WBG)polymers and their morphology control as well as applications in OSCs.Additionally,we introduce our work on binary and ternary blend devices and tandem solar cells containing these materials.

The recent progress of wide bandgap donor polymers towards non-fullerene organic solar cells

This review summarized the recent progress of highly efficient wide bandgap(WBG) donor polymers and their applications in non-fullerene polymer solar cells(NF-PSCs). A brief introduction of the background of WBG donor polymer developments was given. Then the research progress of the reported WBG donor polymers by classification of D-type and DààA type molecular backbones was reviewed. The resulting structure-property correlations of the WBG donor polymers were also discussed to highlight the importance of chemical modifications, which have promoted the great progress of NF-PSC field. Finally,an outlook for future innovations of WBG donor polymers and their NF-PSCs was provided.

Microscopic energy transport through photon-electron-phonon interactions during ultrashort laser ablation of wide bandgap materials Part Ⅰ: photon absorption

The new phenomena induced by femtosecond lasers lead to the new area of ultrafast science.It is a significantchallenge to explain the phenomena associated with complex non-equilibrium and non-linear processes.Althoughthere is a growing body of experimental observation,a comprehensive model remains undeveloped.We reviewthe challenges in understanding the photon absorption stage mainly for the femtosecond ablation of wide bandgap materialsat the intensities of 10^(13)～10^(14) W/cm^2.Major opinions and challenges in ionization mechanisms are presentedby primarily considering multiphoton ionization and avalanche ionization.

一种新型可调驱动电压的SiC/Si混合开关驱动电路

为提高碳化硅金属氧化物半导体场效应晶体管(silicon carbide metal oxide semiconductor filed effect transistor,SiC-MOSFET)与硅基绝缘栅极双极晶体管(silicon insulated gate bipolar transistor,Si-IGBT)并联混合开关(SiC/Si hybrid switch,SiC/Si HyS)的可靠性与适用性,该文提出一种可变驱动电压的SiC/Si HyS栅极驱动电路结构,采用一路脉冲宽度调制(pulse width modulation,PWM)控制信号和一个驱动芯片产生不同电压幅值的栅极控制信号,分别控制SiC/Si HyS中的SiC-MOSFET和Si-IGBT。相比于传统采用2个独立驱动电路的SiC/Si HyS驱动结构,该驱动电路大幅度降低SiC/Si HyS栅极驱动电路的复杂度,降低SiC-MOSFET关断过程中Si-IGBT误导通的可能性,提升混合开关的工作可靠性。该文首先分析所设计驱动电路工作原理,给出驱动电压调节方法;其次,建立耦合电容端电压纹波和系统启动时电容端电压暂态数学模型,通过仿真和实验验证模型准确性;搭建2 kW的SiC/Si混合开关Buck电路,验证该文所提混合开关驱动电路可行性,从SiC/Si HyS功率器件关断损耗、驱动电路功率损耗、成本以及体积4个方面分析所提驱动结构的优势。

Recent progress of parameter-adjustable high-power photonic microwave generation based on wide-bandgap photoconductive semiconductors

Radio frequency/microwave-directed energy sources using wide bandgap SiC photoconductive semiconductors have attracted much attention due to their unique advantages of high-power output and multi-parameter adjustable ability.Over the past several years,benefitting from the sustainable innovations in laser technology and the significant progress in materials technology,megawatt-class output power electrical pulses with a flexible frequency in the P and L microwave wavebands have been achieved by photoconductive semiconductor devices.Here,we mainly summarize and review the recent progress of the high-power photonic microwave generation based on the SiC photoconductive semiconductor devices in the linear modulation mode,including the mechanism,system architecture,critical technology,and experimental demonstration of the proposed high-power photonic microwave sources.The outlooks and challenges for the future of multi-channel power synthesis development of higher power photonic microwave using wide bandgap photoconductors are also discussed.

β-Ga_(2)O_(3)的p型掺杂研究进展

β-Ga_(2)O_(3)具有超宽禁带宽度、高击穿场强、较高的巴利加优值等优点使其成为一种新兴半导体材料,在高功率电子器件、气体传感器、日盲紫外探测器等方面有着极大的应用潜力,但p型掺杂难的问题成为了β-Ga_(2)O_(3)发展的巨大障碍。本文首先简要概述了β-Ga_(2)O_(3)的优点,并介绍了其晶体结构和基本性质。其次,说明了β-Ga_(2)O_(3)的本征缺陷,尤其是氧空位对导电性能的影响。然后,详细讨论了β-Ga_(2)O_(3) p型掺杂的研究现状,包括p型掺杂困难的原因和N掺杂、Mg掺杂、Zn掺杂、其他受主元素掺杂、两种元素共掺杂以及其他方法。最后,总结并对β-Ga_(2)O_(3)未来的发展进行了展望。

光导微波源阵列合成时控技术初步研究

基于宽禁带光导半导体的固态光导微波源是高功率微波产生的一种新途径,该方案具有功率密度高、频带范围宽等特点,且其低时间抖动特性使其在功率合成方面具有巨大潜力,利用光波束形成网络构建光导微波有源相控阵是光导微波器件迈向实用的重要途径。分析了光导微波相控阵系统原理,设计了光导微波真延时网络架构,并构建了差分真延时相控阵和考虑相位随机误差的真延时相控阵的理论模型,对影响功率合成和波束扫描的关键因素开展定量分析和仿真验证。结果表明,对于发射1 GHz信号的n×10阵列,延时均方差在10 ps以下时,指向偏差小于0.13°,峰值增益损耗小于2%;延时步进精度在10 ps以下时,指向偏差小于0.2°,峰值增益损耗小于0.03%。由此提出延时精度指标,为未来更高功率、更大规模的光导微波合成技术发展提供参考。

具有软启动功能的EMI直流滤波器设计

宽禁带半导体器件的应用使电动汽车的电机驱动系统更加小型化和轻量化,但也引发了更为严重的电磁干扰,使得驱动系统的可靠性面临严峻挑战。为此,以24 V/2 A的EMI直流滤波器为例,通过噪声源、滤波器原理及阻抗影响的分析,依据插入损耗指标进行滤波器参数设计。同时,考虑到整车启动时刻的启动冲击,加入软启动电路,进一步提高电动汽车驱动系统可靠性。实验测试验证了滤波器的电磁干扰抑制效果和软启动性能,证明了滤波器设计的可行性和有效性。

2维SnO_(x)/Ga_(2)O_(3)异质结的制备及其探测器的光电性能

紫外探测器在天文、军事、医学等方面具有重要应用前景.采用液态金属转移法制备2维SnO_(x)/Ga_(2)O_(3)异质结,并构建2维SnO_(x)/Ga_(2)O_(3)异质结紫外探测器,研究2维异质结紫外探测器的光电性能.研究结果表明:该文探测器具有良好的光电性能,有潜在应用价值.