Defect Passivation on Lead-Free CsSnI_(3) Perovskite Nanowires Enables High-Performance Photodetectors with Ultra-High Stability

In recent years,Pb-free CsSnI_(3) perovskite materials with excellent photoelectric properties as well as low toxicity are attracting much atten-tion in photoelectric devices.However,deep level defects in CsSnI_(3),such as high density of tin vacancies,structural deformation of SnI_(6)−octahedra and oxidation of Sn^(2+)states,are the major challenge to achieve high-performance CsSnI_(3)-based photoelectric devices with good stability.In this work,defect passivation method is adopted to solve the above issues,and the ultra-stable and high-performance CsSnI_(3) nanowires(NWs)photodetectors(PDs)are fabricated via incorporating 1-butyl-2,3-dimethylimidazolium chloride salt(BMIMCl)into perovskites.Through materials analysis and theoretical calculations,BMIM+ions can effectively passivate the Sn-related defects and reduce the dark current of CsSnI_(3) NW PDs.To further reduce the dark current of the devices,the polymethyl methacrylate is introduced,and finally,the dual passivated CsSnI_(3) NWPDs show ultra-high performance with an ultra-low dark current of 2×10^(-11) A,a responsivity of up to 0.237 A W^(−1),a high detectivity of 1.18×10^(12) Jones and a linear dynamic range of 180 dB.Furthermore,the unpackaged devices exhibit ultra-high stability in device performance after 60 days of storage in air(25℃,50% humidity),with the device performance remaining above 90%.

Large-area perovskite films for PV applications:A perspective from nucleation and crystallization

Perovskite solar cells(PSCs)have attracted significant research interest due to the rapid rise in efficiency.However,a large efficiency gap still exists between laboratory-based small devices and industrialoriented large-scale modules.One of the main reasons for the efficiency losses is the degraded quality and morphology of the deposited large-area films,which is closely associated with crystallization processes.In this review,we discuss the nucleation and crystallization processes in solution and vaporbased up-scaling deposition methods for large-area perovskite films.We review recent scientific achievements and technical developments that have been made in the field of large-area cells.We present the existing problems that limit the performance of large devices and extensively discuss the key influencing parameters from the perspective of nucleation and crystallization over large areas.This review highlights the importance of crystallization control in up-scaling fabrications and presents promising strategies towards large-area perovskite-based optoelectronic devices.

Manipulating the morphology of CdS/Sb_(2)S_(3) heterojunction using a Mg-doped tin oxide buffer layer for highly efficient solar cells

Antimony sulfide(Sb_(2)S_(3))is an appealing semiconductor as light absorber for solar cells due to its high absorption coefficient,appropriate band gap(~1.7 e V)and abundance of constituent elements.However,power conversion efficiency(PCE)of Sb_(2)S_(3)-based solar cells still lags much behind the theoretically predicted due to the imperfect energy level alignment at the charge transporting layer/Sb_(2)S_(3)interfaces and hence severe charge recombination.Herein,we insert a high-temperature sintered magnesium(Mg)-doped tin oxide(SnO_(2))layer between cadmium sulfide(Cd S)and fuorine doped tin oxide to form a cascaded energy level alignment and thus mitigate interfacial charge recombination.Simultaneously,the inserted Mg-doped Sn O_(2)buffer layer facilitates the growth of the neibouring Cd S film with orientation followed by Sb_(2)S_(3)film with larger grains and fewer pinholes.Consequently,the resultant Sb_(2)S_(3)solar cells with Mg-doped SnO_(2)deliver a champion PCE of 6.31%,22.8%higher than those without a buffer layer.Our work demonstrates that deliberate absorber growth as well as efficient hole blocking upon an appropriate buffer layer is viable in obtaining solution-processed Sb_(2)S_(3)solar cells with high performance.

热激活延迟荧光增强型钙钛矿闪烁体及其X射线探测器

金属卤化物钙钛矿材料具有极高的射线衰减系数和优良的光电性能,基于其制备的光电探测器和闪烁体已成功用于X射线和γ-射线探测.然而,充分吸收高能射线需要相对较厚的光吸收层,但所需的厚度对于溶液法制备的钙钛矿薄膜来说很难达到.在这项工作中,我们设计了一种复合型器件,其不需要厚的钙钛矿吸收层,而是利用高荧光效率的钙钛矿闪烁体和性能优良的钙钛矿薄膜光电探测器充分吸收和利用X射线,从而提高X射线探测性能.而考虑到钙钛矿闪烁体严重的自吸收,我们将CsPbBr3与含Cu(Ⅰ)的热激活延迟荧光配合物(MAC^(*))Cu(Cz)混合,有效地实现了下转换发光,最大限度地提高了辐射发光量子效率.与商业闪烁体相比,混合闪烁体还实现了更短的余辉.此外,我们系统地研究对比了CsPbIBr_(2)探测器以及复合型探测器的性能指标,发现复合型探测器对X射线的探测灵敏度有显著提高,并且能够实现在X射线下清晰的成像.这项工作为提高X射线探测性能提供了一种新的思路,在应用层面具有巨大的潜力.

Flexible all-organic photodetectors via universal water-assisted transfer printing

Transfer printing of small-molecular organic semiconductors often faces challenges due to surface adhesion mismatch.Here,we developed a sacrificing-layer-assisted transfer printing technique for the deposition of smallmolecular thin films.High-boiling-point ethylene glycol(EG)was doped in aqueous solution poly(3,4-ethylenedioxythiophene)polystyrene sulfonate(PEDOT:PSS)as the sacrificing layer to manipulate residual water in film,which allowed chlorobenzene solution to spontaneously spread and form uniform film.

通过4-磺基苯甲酸单钾盐抑制离子迁移以实现效率为22.7%的稳定钙钛矿太阳能电池

晶界处的深能级缺陷和严重的卤素离子迁移对进一步提高钙钛矿太阳能电池的稳定性和效率以及消除迟滞现象提出了严峻的挑战.本文报道了一种大尺寸强配位的有机阴离子晶界锚定策略来抑制离子迁移并钝化薄膜缺陷.本策略通过将含有大尺寸有机阴离子的钾盐(4-磺基苯甲酸单钾盐,SAMS)加入到钙钛矿前驱液中来实现.研究表明,阴离子两端的C=O和/或S=O能够与未配位的Pb^(2+)离子和/或卤化物空位之间发生强配位作用,阴离子中的–OH能够与甲脒阳离子形成氢键,以上化学作用使阴离子紧紧锚定在晶界处.SAMS不仅能够钝化浅能级缺陷,而且能够更有效地钝化深能级缺陷.该晶界锚定策略能降低钙钛矿薄膜的缺陷密度、延长载流子寿命和抑制离子迁移,提高电池的效率和稳定性以及消除迟滞效应.结果表明,基于SAMS改性的电池实现了22.7%的效率,而对照器件显示了20.3%的效率.未封装改性的器件在60℃加热老化1320小时后几乎没有发生衰减.