Highly ordered crystallization of α-FAPbl_(3) films via homogeneous seeds for efficient perovskite solar cells

Formamidine lead triiodide(FAPbI_(3))perovskites have become the most promising photovoltaic materials for perovskite solar cells with record power conversion efficiency(PCE).However,random nucleation,phase transition,and lattice defects are still the key challenges limiting the quality of FAPbI_(3) films.Previous studies show that the introduction or adding of seeds in the precursor is effective to promote the nucleation and crystallization of perovskite films.Nevertheless,the seed-assisted approach focuses on heterogeneous seeds or hetero-composites,which inevitably induce a lattice-mismatch,the genera-tion of strain or defects,and the phase segregation in the perovskite films.Herein,we first demonstrate that high-quality perovskite films are controllably prepared using α-and δ-phases mixed FAPbI_(3) micro-crystal as the homogeneous seeds with the one-step antisolvent method.The partially dissolved seeds with suitable sizes improve the crystallinity of the perovskite flm with preferable orientation,improved carrier lifetime,and increased carrier mobility.More importantly,the α-phase-containing seeds promote the formation of α-phase FAPbI_(3) films,leading to the reduction of residual lattice strain and the suppres-sion of I-ion migration.Besides,the adding of dimethyl 2,6-pyridine dicarboxylate(DPD)into the pre-cursor further suppresses the generation of defects,contributing to the PCE of devices prepared in air ambient being significantly improved to 23.75%,among the highest PCEs for fully air-processed FAPbI_(3) solar cells.The unpackaged target devices possess a high stability,maintaining 80%of the initial PCE under simulated solar illumination exceeding 800 h.

Technoeconomically competitive four-terminal perovskite/graphenesilicon tandem solar cells with over 20% efficiency

Perovskite/Silicon(PS) tandem solar cells have attracted much interest over recent years. However, the most popular crystalline silicon solar cells utilized in tandems require complicated fabrication processes mainly including texturization, diffusion, passivation and metallization, which takes up much cost in photovoltaic market. Here, we report a facile graphene/silicon(Gr/Si) solar cell featuring of lowtemperature( 200 °C) processing and an efficiency of 13.56%. For reducing the heat dissipation loss of high energy photon, the perovskite solar cell(PSC) with a wide band gap of 1.76 e V was adopted as the top cell for the tandem. To reduce the loss of parasitic absorption in hole transport layers(HTLs),thickness of Spiro-OMe TAD is re-optimized by compromising the efficiency and the optical transmittance of the devices. As a result, the semitransparent top perovskite solar cell yields a highest efficiency of13.35%. Furthermore, we firstly achieved a low-temperature-processed four-terminal(4-T) perovskite/graphene-silicon(PGS) heterojunction tandem solar cell with the efficiency of 20.37%. The levelized cost of electricity(LCOE) of PGS 4-T modules were estimated to a competitive price, exhibiting much greater potential for practical application compared to that of PS 4-T modules.

高效稳定钙钛矿太阳能电池中非晶和缺陷表面的重构

钙钛矿太阳能电池的表界面性质是影响器件效率和稳定性的关键性因素.本文中,我们首次发现空穴传输层中的添加剂4-叔丁基吡啶(tBP)可以将钙钛矿非晶态和缺陷表面层进行重结晶,并且钝化晶粒表面的缺陷位点.该重构可使钙钛矿的表面功函数增大,降低了钙钛矿与空穴传输层之间的界面能级失配,提高了器件的光电压.进一步地,我们通过化学键合强度设计,开发了更有效的空穴传输层添加剂4-叔丁基哌啶(tBPp),它比tBP具有与钙钛矿表面缺陷位点更强的相互作用.得益于吸附能的增强,经tBPp重构的钙钛矿表面缺陷态密度降低,且在热、光、湿度的作用下稳定性更好.基于tBPp作为添加剂的钙钛矿电池最高效率达到了24.2%.在氮气气氛中进行最大功率点跟踪测试,未封装的设备在连续光照超过1200小时后几乎可以保持其初始效率.本工作全面揭示了空穴传输层中添加剂对于钙钛矿电池的效率和稳定性的重要性,并提供了系统和基础性理解.

Light-Emitting Artificial Synapses for Neuromorphic Computing

As the key connecting points in the neuromorphic computing systems,synaptic devices have been investigated substantially in recent years.Developing optoelectronic synaptic devices with optical outputs is becoming attractive due to many benefits of optical signals in systems.

直拉硅单晶的杂质工程:微量掺锗的效应

直拉硅单晶是集成电路的基础材料,因而在过去几十年来被广泛而深入研究.直拉硅单晶的缺陷以及机械强度对集成电路制造的成品率有显著的影响.传统上,人们认为直拉硅单晶中除了掺杂所需的电活性杂质以及不可避免的氧杂质以外,其他杂质越少越好.在此情形下,直拉硅单晶的缺陷控制和机械强度的改善几乎只能依赖于晶体生长工艺的优化.为了打破这种限制,我们提出在直拉硅单晶中掺入特定的非电活性杂质,既可以通过这些杂质原子与点缺陷的相互作用来调控维度更高的缺陷的行为,又可以发挥增强机械强度的作用,这就是直拉硅单晶的杂质工程.本文首先阐述直拉硅单晶的杂质工程的研究背景与意义,随后综述作为直拉硅单晶的杂质工程的一个范本——微量掺锗的效应,包括掺锗对氧沉淀和空洞等缺陷形成的影响及其对集成电路制造的有益作用,以及掺锗对硅片机械强度的增强作用.

不同官能团对钙钛矿太阳电池的钝化效果

为了提高钙钛矿太阳能电池的效率和稳定性,许多具有不同官能团的有机分子已被报道用来钝化钙钛矿表面.然而,不同官能团与其钝化效果的内在关联性却很少被人们了解.本文系统研究和比较了12种不同官能团对钙钛矿太阳电池的钝化作用,结果表明,钝化效果和电池的开路电压随着钝化分子与钙钛矿表面缺陷化学键合强度的增加而具有增加趋势.并且其中四叔丁基苯甲酸可以通过分子间的额外氢键作用,形成具有不溶于水和高熔点的晶体界面层,可以进一步稳定钙钛矿薄膜表面的钝化效果.得益于与钙钛矿的强配位作用和自身的氢键作用,基于四叔丁基苯甲酸钝化的钙钛矿电池获得了21.46%效率.更重要的是,这些器件在45%相对湿度下储存了1年以上(10,080小时),仍能保持88%的初始性能.该工作对于理解钙钛矿表界面的钝化以及进一步提高钙钛矿太阳电池性能和稳定性具有积极借鉴意义.

Visible-blind short-wavelength infrared photodetector with high responsivity based on hyperdoped silicon

Developing a low-cost, room-temperature operated and complementary metal-oxide-semiconductor(CMOS)compatible visible-blind short-wavelength infrared(SWIR) silicon photodetector is of interest for security,telecommunications, and environmental sensing. Here, we present a silver-supersaturated silicon(Si:Ag)-based photodetector that exhibits a visible-blind and highly enhanced sub-bandgap photoresponse. The visible-blind response is caused by the strong surface-recombination-induced quenching of charge collection for short-wavelength excitation, and the enhanced sub-bandgap response is attributed to the deep-level electrontraps-induced band-bending and two-stage carrier excitation. The responsivity of the Si:Ag photodetector reaches 504 mA · W^(-1) at 1310 nm and 65 m A · W^(-1) at 1550 nm under-3 V bias, which stands on the stage as the highest level in the hyperdoped silicon devices previously reported. The high performance and mechanism understanding clearly demonstrate that the hyperdoped silicon shows great potential for use in optical interconnect and power-monitoring applications.

Bioinspired molecules design for bilateral synergistic passivation in buried interfaces of planar perovskite solar cells

Trap-mediated energy loss in the buried interface with non-exposed feature constitutes one of the serious challenges for achieving high-performance perovskite solar cells(PSCs).Inspired by the adhesion mechanism of mussels,herein,three catechol derivatives with functional Lewis base groups,namely 3,4-Dihydroxyphenylalanine(DOPA),3,4-Dihydroxyphenethylamine(DA)and 3-(3,4-Dihydroxyphenyl)propionic acid(DPPA),were strategically designed.These molecules as interfacial linkers are incorporated into the buried interface between perovskite and SnO_(2) surface,achieving bilateral synergetic passivation effect.The crosslinking can produce secondary bonding with the undercoordinated Pb^(2+) and Sn^(4+) defects.The PSCs treated with DOPA exhibited the best performance and operational stability.Upon the DOPA passivation,a stabilized power conversion efficiency(PCE)of 21.5%was demonstrated for the planar PSCs.After 55 days of room-temperature storage,the unencapsulated devices with the DOPA crosslinker could still maintain 85%of their initial performance in air under relative humidity of-15%.This work opens up a new strategy for passivating the buried interfaces of perovskite photovoltaics and also provides important insights into designing defect passivation agents for other perovskite optoelectronic devices,such as light-emitting diodes,photodetectors,and lasers.

An industrial solution to light-induced degradation of crystalline silicon solar cells

Boron-oxygen defects can cause serious lightinduced degradation （LID） of commercial solar cells based on the boron-doped crystalline silicon （c-Si）, which are formed under the injection of excess carriers induced either by illumination or applying forward bias. In this contribution, we have demonstrated that the passivation process of boron-oxygen defects can be induced by applying forward bias for a large quantity of solar cells, which is much more economic than light illumination. We have used this strategy to trigger the passivation process of batches of aluminum back surface field （A1-BSF） solar cells and passivated emitter and rear contact （PERC） solar cells. Both kinds of the treated solar cells show high stability in efficiency and suffer from very little LID under further illumination at room temperature. This technology is of significance for the suppression of LID of c-Si solar cells for the industrial manufacture.

非晶硅/晶体硅异质结太阳电池中的光致增强现象

硅异质结(SHJ)太阳电池由于具有本征非晶硅/掺杂非晶硅的双层膜结构,表现出了优异的钝化特性.在本文中,我们在加热光照条件下研究了SHJ太阳电池的少子寿命变化情况,发现其会有明显提升.通过分析饱和电流密度(J_(0))的数值变化,将此现象归因于SHJ太阳电池的表面钝化质量提高.基于以上实验结果,利用指数函数拟合模型可以提取出不同温度下光致增强的速率,并利用阿伦尼乌斯拟合,得到光致增强的激活能为0.47 eV,这说明钝化质量提高与非晶硅层中的氢扩散有关.此外,稳定性测试结果显示SHJ太阳电池的增强效果可以维持至少1000小时.本研究结果对于理解SHJ太阳电池的光致增强机理及其实际应用十分有意义,有助于进一步推进全球光伏产业的发展.

自整流效应的忆阻器用于类脑计算

Considering the challenges arising from the von Neumann bottleneck and the end of Moore’s law,people have been seeking for new ways for future computing[1].The human brain is a highly parallel and low-energy-consumption computing system and capable of implementing complicated cognitive tasks[2].

Manipulating the film morphology evolution toward green solvent-processed perovskite solar cells

High-performance perovskite solar cells(PVSCs)with low energy consumption and green processing are highly desired,but constrained by the difficulty in morphology control and the poor understanding on morphology evolution mechanisms.To address this issue,here we studied the effect of antisolvents on the perovskite film formation.We found that both the antisolvents and the perovskite composition affect the perovskite film morphology greatly via influencing the intermediate phase,and different perovskite compositions require different antisolvents to reach the optimal morphology.This provides the opportunity to achieve high-performance PVSCs with green antisolvent,that is,isopropanol(iPA)by changing the perovskite compositions,and leads to a powerconversionefficiency(PCE)of 21.50% for PVSCs based on MA_(0.6)FA_(0.4)PbI_(3).Further,we fabricated“fully green”PVSCs with all layers prepared by green sol-vents,and the optimal PCE can reach 19%,which represents the highest among PVSCs with full-green processing.This work provides insight into the perovskite morphology evolution and paves the way toward“green”processing PVSCs.