二氧化钛/量子点超薄膜/CsSnI3体异质结全无机高效固态太阳电池研究

In the core steps of light-to-electricity conversion processes in quantum dot solar cells,there exist three key problems hindering further improvement in power conversion efficiency. Firstly,the exciton dissociation efficiency in the cells is very low. Secondly,the electron-hole recombination in the cells is serious in charge transfer processes. Moreover,disparity between the electron and hole scavening rate in the cells leads to further accumulation of electrons or holes within the quantum dots and increases the rate of electron-hole recombination.In order to overcome these problems,the proposal will carry out the research on high-efficiency all-ionrganic solid-state solar cells based on TiO2/ultrathin quantum dot film/CsSnI3 bulk- heterojunction. The proposers come up with the following designs: ①TiO2 nanowire/nanotube arrays are used to improve electron transfer rate, diffusion length and suppress dark reaction; the CsSnI3 high-speed hole transport material is used to improve hole transport rate and eliminate secondary electron-hole recombination. ②Ultrathin quantum dot film with suitable energy band structure and TiO2/ultrathin quantum dot film/CsSnI3 based 3D network and coaxial bulk-heterojunctions are fabricated for improving exciton dissociation efficiency and decreasing recombination losses. ③ the utilized inorganic materials show good physical and chemical properties and stability, which can prolong the lifetime of the solar cells and increase their long-term stability . When the research project is finished, it is expected to reveal the basic rules and regulating mechanisms associated with the conversion processes from photons → excitons → free carriers and the charge collection processes, and successfully fabricate long-term stable and high-efficiency solar cells. The research results are useful for fabricating the same kind of solar cells by supplying the obtained theoretic and technical supports. They are also meaningful in the fields such as controllable assembly of quantum dot based optoelectronic devices, interface science, and electrochemistry science at the same time.

针对量子点太阳电池光电转换过程激子解离效率低、电子空穴传输过程复合严重及传输速率不匹配导致载流子滞留引起二次复合等问题，本项目拟开展二氧化钛/量子点超薄膜/CsSnI3体异质结全无机高效固态太阳电池研究：①用二氧化钛纳米线/管阵列提高电子传输速率、扩散距离和抑制暗反应；用CsSnI3高速空穴传输材料提高空穴传输速率，消除载流子二次复合；②制备能级适宜的量子点超薄膜，构建二氧化钛/量子点超薄膜/CsSnI3间三维网络及同轴有序体异质结，促进激子解离，降低复合损耗；③无机材料具有较好的物理和化学性能及稳定性，能有效延长所构建电池的工作寿命，提高其长程稳定性。本项研究将揭示该结构电池在光子→激子→自由载流子转换及电荷收集过程的基本规律和调控机制，获得稳定高效的全无机量子点太阳电池，为同类电池的研发提供理论和技术支撑，研究结果在量子点光电器件、界面科学、电化学等领域也具有重要科学意义。

针对量子点太阳能电池光电转换过程激子解离效率低、电子空穴传输过程复合严重及传输速率不匹配导致载流子滞留引起二次复合等问题，本项目开展了TiO2/量子点超薄膜/CsSnI3体异质结全无机高效固态太阳能电池的研究，主要内容包括：①用TiO2纳米线/纳米管阵列提高电子传输速率、扩散距离和抑制暗反应；用CsSnI3高速空穴传输材料提高空穴传输速率，消除载流子二次复合；②制备能级适宜的量子点超薄膜，构建TiO2/量子点超薄膜/CsSnI3间三维网络及同轴有序体异质结，促进激子解离，降低复合损耗；③将相关材料拓展应用到有机无机杂化钙钛矿太阳能电池中，构建高效稳定的钙钛矿太阳能电池。经过四年潜心研究，系统掌握了溶剂热法合成单分散、高结晶度、高质量的半导体金属氧化物及硫族化合物量子点、纳米晶颗粒或纳米棒，水热法合成TiO2纳米线阵列及复杂多级结构，阳极氧化法制备TiO2纳米管有序阵列及原位转变成交叠生长的单晶锐钛矿相TiO2纳米晶颗粒，溶液法制备高质量CsSnI3固态空穴传输材料及其它杂化钙钛矿材料。成功构建了以TiO2量子点为阻挡层，TiO2纳米线/纳米管阵列为光阳极，量子点超薄膜为敏化层，CsSnI3为固态空穴传输层的高效稳定全无机固态太阳能电池。同时，这些半导体氧化物及硫族化合物量子点或纳米材料和TiO2纳米线/纳米管阵列也被用来制备高性能空穴阻挡层、电子传输层、空穴传输层和光阳极应用于高效染料/量子点敏化太阳能电池和杂化钙钛矿太阳能电池中。项目取得良好成果，发表SCI收录论文38篇，其中影响因子5以上JCR一区论文17篇；在国内著名学术期刊《中国科学：化学》上发表1篇论文；获授权中国发明专利6项；培养研究生8名。通过系统分析研究数据提炼内在机理，揭示了相关器件界面匹配、能级匹配和结构匹配规律和调控机制，为同类太阳能电池的研制提供理论和技术支撑，研究结果在量子点及钙钛矿光电器件、界面科学、电化学等领域也具有重要科学意义。