Single‑Layer ZnO Hollow Hemispheres Enable High‑Performance Self‑Powered Perovskite Photodetector for Optical Communication

The carrier transport layer with reflection reduction morphology has attracted extensive attention for improving the utilization of light.Herein,we introduced single-layer hollow ZnO hemisphere arrays(ZHAs)behaving light trapping effect as the electron transport layer in perovskite photodetectors(PDs).The singlelayer hollow ZHAs can not only reduce the reflection,but also widen the angle of the effective incident light and especially transfer the distribution of the optical field from the ZnO/FTO interface to the perovskite active layer confirmed by the 3D finitedifference time-domain simulation.These merits benefit for the generation,transport and separation of carriers,improving the light utilization efficiency.Finally,our optimized FTO/ZHA/CsPbBr3/carbon structure PDs showed high self-powered performance with a linear dynamic range of 120.3 dB,a detectivity of 4.2×10^(12) Jones,rise/fall time of 13/28μs and the f_(−3) dB of up to 28 kHz.Benefiting from the high device performance,the PD was demonstrated to the application in the directional transmission of encrypted files as the signal receiving port with super high accuracy.This work uniquely utilizes the features of high-performance self-powered perovskite PDs in optical communication,paving the path to wide applications of all-inorganic perovskite PDs.

Post Adaptability of Graduates-A Case Study of Business English Majors from H University

In recent years,the number of graduates in employment has increased significantly because of a boom in the number of graduates along with the advancement of the Enrollment Expansion Plan of Colleges and Universities in China.The issues about career selection and graduate employment have been enthusiastically discussed in academic circles as these issues are constantly emphasized by all walks of life.However,academic researchers often neglect matters pertaining graduates when they are already holding positions.This study believes that being employed is not the end point,but a new start,which means that matters pertaining graduates after being employed should also be cared about.This study specifically focuses on the post adaptability of graduates after being employed.In this study,through questionnaires,a number of employed Business English majors from the graduating class of 2011 to 2016 at H university in Shaanxi Province were selected.After that,using the variables from The Fitness Subscale of Adolescent Mental Health Quality Questionnaire,the participants5 post adaptability was studied.

Ultrasensitive,flexible perovskite nanowire photodetectors with long-term stability exceeding 5000 h

Photodetectors(PDs)based on perovskite nanowires are among the most promising next-generation photodetection technologies;however,their poor long-term stability is the biggest challenge limiting their commercial applica-tion.Herein,an ionic liquid,1-butyl-3 methylimidazolium tetrafuoroborate(BMIMBF_(4)),is incorporated as an additive into methylammonium lead tri-iodide(MAPbI_(3))nanowires;this not only effectively passivates defects to inhibit perovskite degradation but also leads to the formation of nanochannels,enabling fast charge transfer.As a result,the long-term stability and perfor-mance of MAPbI_(3)nanowires are considerably improved.The detectivity,linear detection range,and noise equivalent power of the MA PbI_(3)nanowire PD reach 2.06×10^(13)Jones,160dB,and 1.38×10^(-15)W Hz-^(1/2),respectively,compara-ble to the highest performance of perovskite nanowire PDs reported to date.Moreover,the unencapsulated PD can maintain 100%of its initial performance after being exposed to an open-air environment for more than 5000 h,esta-blishing it as the most stable perovskite nanowire PD reported to date.Nota-bly,the PD exhibits improved diffuse reflection imaging ability when compared with commercial silicon photodiode S2386.This study provides a new strategy for constructing sensitive,stable,and flexible perovskite PDs and will accelerate their commercial application in the future.

Space-confined growth of high-quality CsBi3I10 lead-free perovskite film for near-infrared photodetectors with high sensitivity and stability

As a lead-free perovskite,CsBi3I10 has attracted significant attention because of its high thermal tolerance and long electron diffusion length.Solution-processed high-performance CsBi3I10 perovskite devices,however,are hindered by the formation of a two-dimensional structure,which results in an extremely high surface roughness and many pinholes.In this paper,we reported a space-confined growth(SCG)method using a single-layer polystyrene(PS)sphere template to obtain high-smoothness,high-crystallinity,and dense CsBi3I10 perovskite films.Compared with traditionally spin-coated CsBi3I10 photodetectors(PDs),the metal-semiconductor-metal PDs made by SCG showed a higher photocurrent,a lower dark current,and a bigger on/off ratio.In addition,the photocurrent of our unencapsulated CsBi3I10 perovskite PDs was not attenuated under long-time illumination.In addition,when the device was stored in air for 30 d,its performance also showed no degradation,demonstrating ultra-high stability.Furthermore,the synthesis was free of antisolvents,such as chlorobenzene and toluene,which is beneficial for the environmentally friendly assembly of the devices.Our strategy opens up a new way to prepare high-quality lead-free perovskite,which may be useful for applications in light-emitting diodes and solar cells.

High-performance Ag_(2)BiI_(5)Pb-free perovskite photodetector

Recently,lead-free all-inorganic halide perovskites have attracted great interest because they not only have the merits of the halide perovskite family,but also are non-toxic.However,the commercialization of lead-free allinorganic perovskites is restricted by their relatively low performances,which are usually caused by the fabrication methods and undesirable interfaces between the active layer and carrier transport layers.Herein,we demonstrate a solution-processed route for high-quality Ag_(2)BiI_(5) lead-free perovskite film by adopting ideal electron transport material SnO_(2)and a carbon electrode.By optimizing the fabrication process and tailoring the composition of the perovskite active layer,a high-performance photodetector(PD)with an FTO∕SnO_(2)∕Ag_(2)BiI_(5)∕carbon structure PD is first fabricated,which shows good self-powered performance with a detectivity of as high as 5.3×10^(12)Jones and a linear dynamic range of up to 138 d B,which are better than those of the reported Pb-free perovskite PDs and comparable to high-performance Pb-based perovskite PDs.In addition,our unpackaged PDs show good light,thermal,and storage stability in air.Our results provide a special route for the development of lead-free perovskite devices in an environmentally friendly field.