UV light absorbers executing synergistic effects of passivating defects and improving photostability for efficient perovskite photovoltaics

Metal halide perovskite-based solar cells(PSCs) have rapidly-increased power conversion efficiency(PCE)exceeding 25% but poor stability especially under ultraviolet(UV) light. Meanwhile, non-radiative recombination caused by diverse defects in perovskite absorbers and related interfaces is one of the major factors confining further development of PSCs. In this study, we systematically investigate the role of 2-(2-hydroxy-5-methylphenyl)benzotriazole(UVP) additive in perovskite layers. By adjusting the amount of doped UVP, the quality of perovskite absorbers is significantly improved with enlarged grains, longer lifetime and diffusion length of charge carriers. Furthermore, UVP not only reduces defects for less nonradiative recombination, but also matches energy level alignment for efficient interfacial charge extraction. X-ray photoelectron spectroscopy confirms that N-donor of UVP molecule coordinates with undercoordinated Pb^(2+) on the surface. Interestingly, UVP incorporated in PbI_(2) protects the perovskite by absorbing UV through the opening and closing of the chelating ring. Eventually, the UVP treated PSCs obtain a champion PCE of 22.46% with remarkably enhanced UV stability, retaining over 90% of initial PCE after 60 m W/cm^(2) strong UV irradiation for 9 h while the control maintaining only 74%. These results demonstrate a promising strategy fabricating passivated and UV-resistant perovskite materials simultaneously for efficient and stable perovskite photovoltaics.

Design of Intelligent Mosquito Nets Based on Deep Learning Algorithms

An intelligent mosquito net employing deep learning has been one of the hotspots in the field of Internet of Things as it can reduce significantly the spread of pathogens carried by mosquitoes,and help people live well in mosquito-infested areas.In this study,we propose an intelligent mosquito net that can produce and transmit data through the Internet of Medical Things.In our method,decision-making is controlled by a deep learning model,and the proposed method uses infrared sensors and an array of pressure sensors to collect data.Moreover the ZigBee protocol is used to transmit the pressure map which is formed by pressure sensors with the deep learning perception model,determining automatically the intention of the user to open or close the mosquito net.We used optical flow to extract pressure map features,and they were fed to a 3-dimensional convolutional neural network(3D-CNN)classification model subsequently.We achieved the expected results using a nested cross-validation method to evaluate our model.Deep learning has better adaptability than the traditional methods and also has better anti-interference by the different bodies of users.This research has the potential to be used in intelligent medical protection and large-scale sensor array perception of the environment.

Simulation and application of external quantum efficiency of solar cells based on spectroscopy

In this study,a method for optical simulation of external quantum efficiency(EQE)spectra of solar cells based on spectroscopy is proposed,which is based on the tested transmittance and reflectance spectra.First,to obtain a more accurate information of refractive index and extinction coefficient values,we modified the reported optical constants from the measured reflectance and transmittance spectra.The obtained optical constants of each layer were then collected to simulate the EQE spectra of the device.This method provides a simple,accurate and versatile way to obtain the actual optical constants of different layers.The EQE simulation approach was applied to the flat and textured heterojunctions with intrinsic layers(HIT)solar cells,respectively,which showed a perfect matching between the calculation results and the experimental data.Furthermore,the specific optical losses in different devices were analyzed.

3D nano-printed geometric phase metasurfaces for generating accelerating beams with complex amplitude manipulation

Metasurface,a forefront in emerging optical devices,has demonstrated remarkable potential for complex amplitude manipulation of light beams.However,prevailing approaches face challenges in spatial resolution and complexities associated with integrating dynamic phases,impeding the simplified design and reproducible fabrication of metasurfaces.Here,we introduce an innovative approach for complex amplitude modulation within 3D nano-printed geometric phase metasurfaces.Our approach enables the generation of self-accelerating beams by encoding amplitude through phase-only manipulation,achieving high spatial resolution.Notably,this method circumvents the conventional need to adjust the geometric parameters of metasurface unit structures for amplitude manipulation,offering a streamlined and efficient route for design and fabrication complexity.This novel methodology holds promise for expedited and low-cost manufacturing of complex amplitude manipulation metasurfaces.

Highly efficient bifacial semitransparent perovskite solar cells based on molecular doping of CuSCN hole transport layer

Coper thiocyanate(CuSCN)is generally considered as a very hopeful inorganic hole transport material(HTM)in semitransparent perovskite solar cells(ST-PSCs)because of its low parasitic absorption,high inherent stability,and low cost.However,the poor electrical conductivity and low work function of CuSCN lead to the insufficient hole extraction and large open-circuit voltage loss.Here,2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane(F4TCNQ)is employed to improve conductivity of CuSCN and band alignment at the CuSCN/perovskite(PVK)interface.As a result,the average power conversion efficiency(PCE)of PSCs is boosted by≈11%.In addition,benefiting from the superior transparency of p-type CuSCN HTMs,the prepared bifacial semitransparent n-i-p planar PSCs demonstrate a maximum efficiency of 14.8%and 12.5%by the illumination from the front side and back side,respectively.We believe that this developed CuSCN-based ST-PSCs will promote practical applications in building integrated photovoltaics and tandem solar cells.

Pattern recognition receptors in zebrafish provide functional and evolutionary insight into innate immune signaling pathways

Pattern recognition receptors （PRRs） and their signaling pathways have essential roles in recognizing various components of pathogens as well as damaged cells and triggering inflammatory responses that eliminate invading microorganisms and damaged cells. The zebrafish relies heavily on these primary defense mechanisms against pathogens. Here, we review the major PRR signaling pathways in the zebrafish innate immune system and compare these signaling pathways in zebrafish and humans to reveal their evolutionary relationship and better understand their innate immune defense mechanisms.

有机太阳电池关键材料研究进展

有机太阳电池具有质量轻、柔性、印刷制备等优点,有巨大的应用潜力,从其诞生那一刻起便引起了学术界和工业界的广泛研究兴趣.历经25年的发展,有机太阳电池效率已突破18%,其快速进步得益于不断涌现的高性能新材料和器件制备技术,以及对电池活性层形貌、分子堆积和器件机理的深入理解.基于有机共轭结构的电子给体和电子受体材料是决定有机太阳电池性能的关键材料.本文将以给、受体材料的发展历程为主线,聚焦那些明星材料和里程碑工作,阐述高性能关键材料的分子结构演变和进化过程,最后展望其面临的挑战和未来发展方向.

Progress of the key materials for organic solar cells

Organic solar cells have attracted academic and industrial interests due to the advantages like lightweight,flexibility and roll-to-roll fabrication.Nowadays,18%power conversion efficiency has been achieved in the state-of-the-art organic solar cells.The recent rapid progress in organic solar cells relies on the continuously emerging new materials and device fabrication technologies,and the deep understanding on film morphology,molecular packing and device physics.Donor and acceptor materials are the key materials for organic solar cells since they determine the device performance.The past 25 years have witnessed an odyssey in developing high-performance donors and acceptors.In this review,we focus on those star materials and milestone work,and introduce the molecular structure evolution of key materials.These key materials include homopolymer donors,D-A copolymer donors,A-D-A small molecular donors,fullerene acceptors and nonfullerene acceptors.At last,we outlook the challenges and very important directions in key materials development.

无机材料对高效钙钛矿太阳能电池缺陷的钝化

用有机材料进行表面钝化是提高钙钛矿太阳电池稳定性和效率的有效策略之一.但是,有机分子和钙钛矿层之间不牢固的键合作用仍不足以钝化各种缺陷以保护钙钛矿层免受氧气和水的侵蚀.最近,由于无机材料更稳定的化学键和更有效的钝化效果而逐渐成为研究的热门.含铅物质、碱金属卤化物、过渡元素卤化物、氧化物、疏水性物质等材料已被应用于钙钛矿太阳能电池表界面缺陷的钝化.这些无机材料通过控制钙钛矿的成核结晶过程以及形成物理保护层显著提高了器件的稳定性和效率.

单晶钙钛矿器件

Currently,perovskite solar cells(PSCs)based on polycrystalline absorbers reach a certified power conversion efficiency(PCE)of25.2%[1].However,the further advance of the PCE has been impeded by intrinsic defects located at the surface or grain boundaries of polycrystalline perovskite films[2–4].