钙钛矿太阳能电池用无机空穴传输材料CuI的表面钝化及相关机理研究

Perovskite solar cell (PSC) is one of the most important researches in photovoltaic field. PSC photocathode hole transport materials (HTM) are almost all organic materials which are of low carrier mobility, complex preparation, high cost. So it is very important to look for stable and efficient, environmental friendly, low cost materials for the PSC industrialization. Inorganic p-type semiconductor CuI has been successfully used in PSC, but excessive iodine which are absorbed on the surface result not only the high conductivity of CuI but also the low photoelectric conversion efficiency (PCE). If the proper passivation is done on the surface of CuI, PCE can be increased when the electrical properties of CuI can meet the requirements of the photocathode. So the applicants proposed the environmental inorganic-material@CuI core-shell particles are prepared by sol-gel method. The influence rules of synthesis conditions on the micro structure morphology of particles will be researched and the controllable preparation will be realized. The formation mechanism of core-shell structure will be studied. The mechanism of the effect of the shell material kinds and shell thickness on the surface state of CuI thin films and electrical properties will be studied and the carrier transport mechanism will be revealed. Then the inorganic-material@CuI thin films are prepared as HTM for PSC, the carrier transport behavior is studied and the carrier transport model will be established. This project provides a new idea for the performance optimization of low cost inorganic HTM used in solar cells. It has important research significance and application value.

钙钛矿太阳能电池(PSC) 是光伏领域最重要研究之一。PSC光阴极空穴传输层(HTM)几乎均为有机材料，而它们载流子迁移率低，合成工艺复杂，价格昂贵，因此寻找高效稳定、环境友好、低成本材料对PSC工业化尤为重要。无机p型半导体CuI已成功用于PSC，但其表面吸附的过量碘既是高导电性根源，亦会降低电池光电转换效率(PCE)。若对CuI适当表面钝化，则可在满足光阴极电学性能要求前提下提高PCE。故申请者提出采用溶胶-凝胶法，制备环保无机物@CuI核壳结构粒子，系统研究合成条件对粒子微细结构形貌等影响规律，实现可控制备；研究核壳结构形成机理，研究壳层材料及壳层厚度等对CuI薄膜表面态及电学性能的影响机理，揭示核壳之间载流子迁移机制；将无机物@CuI粒子制得薄膜用于PSC，研究载流子输运行为，建立载流子输运模型。本项目为太阳能电池用低成本无机HTM性能优化提供了新思路，具有重要研究意义和应用价值。

钙钛矿太阳能电池被期刊Science 列为2013 年度的世界十大科技进展之一，这类电池因其吸收层钙钛矿材料转换效率高，电池制备工艺适于大规模生产，可用于柔性器件，因此其产业化具有非常诱人的前景。然而当前电池结构中广泛应用的有机HTM载流子迁移率低，合成工艺复杂，价格昂贵，严重制约了电池的产业化进程。无机p型半导体碘化亚铜由于具有高电导率、良好的化学稳定性、容易合成、低成本等优点，成为一个理想的替代者。尽管如此，CuI的高电导率依赖于表面吸附的过量碘，然而吸附碘却在价带形成陷阱态，增加了载流子复合率，从而降低电池转换效率。本项目首次尝试采用溶胶凝胶法制备CuI及Al2O3/CuI材料，获得了所需产物，但纯度及组分有待优化。受此影响，后续采用沉淀-溶胶凝胶结合法制备了Al2O3/CuI材料，获得了相对合适的合成条件。提出了一种简单易行的有水双喷沉淀法，制备出了粒径较小且分布均匀的CuI材料，用其制备浆料并涂膜，研究了薄膜形貌及光电性能。此外，项目的提出背景是钙钛矿太阳能电池的性能改善，因此还研究了不同衬底对甲胺铅碘层稳定性的影响。具体重要的研究结果如下：.1）初次尝试采用溶胶凝胶法制备CuI材料，研究发现溶胶过滤、添加适量PEG、不加HCl的条件下有利于较小粒径CuI的获得； .2）提出了一种简单易行的有水双喷沉淀法，制备出了粒径较小且分布均匀的CuI材料。.3）采用沉淀-溶胶凝胶结合法制备了Al2O3/CuI材料，结果表明一步溶胶法不能获得Al2O3/CuI材料；氧化铝溶胶陈化时间2天及复合材料煅烧时间1h所得产物性能最佳。.4）首次制备了CuI浆料，研究了粉体粒径、溶剂种类对浆料稳定性的影响，结果表明粉体粒径小易于获得稳定浆料，同时乙醇在所选用的四种溶剂中性能最佳。.5）用CuI浆料涂膜，研究发现旋涂法工艺及乙醇溶剂浆料的选用易于获得致密性、电阻率较低的薄膜。.6）研究了不同衬底对甲胺铅碘层稳定性的影响。结果表明，70℃下，甲胺铅碘在载玻片上最为稳定，在AZO和ITO上易于分解。