钙钛矿太阳能电池的环境稳定性及退化机制的同步辐射原位实时研究

Solar energy is one of the priorities among the green energy sources to be developed in China.Due to their excellent conversion efficiencies, Perovskite solar cells, which recently have been developed rapidly, have drawn wide interests.However, there are still many problems to be solved before they can be put into market,especially the device of humidity, light, heat and other environmental factors are very sensitive and devices with low yield. As an example, the structure, crystalline size, the distribution of the bore diameter, and the coverage of the Perovskite film in the Perovskite planar hetero-junction solar cells are critical to their performances, which demands lots of research efforts to realize high quality Perovskite thin films.This proposal will take use of the synchrotron based techniques to focus on the preparation will decide the structures and morphologies as well as thus their performances.Especially, In-situ and real time studies will be applied during the preparation of Perovskite thin films using device thermal stability and film microstructure and morphology techniques. The structures as well as electronic structures of the prepared films will be further characterized by other in-situ or ex-situ techniques. Finally, Perovskite planar hetero-junction solar cells will be prepared and their performances will be tested. The goal is to reveal the relationships between the preparation, working process and the structures as well as morphologies, and thus their relationships to the electric properties, the charge carrier transport properties, and the optical energy conversion efficiency, including the relationships between the Perovskite/ charge transport layer interface microstructures and the charge transport properties. With help of thermal stability in-situ test, a deeper understanding of the working mechanism of the Perovskite solar cells will be realized, which will guide further work to optimize their preparation and finally put them into the market.

太阳能是各国优先发展的绿色新能源之一。钙钛矿太阳能电池近来由于其优异性能受到广泛关注，然而其产业化应用仍然面临着一系列亟待解决的问题，尤为突出的是钙钛矿薄膜极易受环境因素（光、热、湿度）的影响，致使器件的效率和环境稳定性大幅降低，然而其影响机理和退化机制仍不明确，因此大幅提高钙钛矿太阳能电池的效率和环境稳定性仍需系统综合性的研究。本项目计划采用同步辐射技术原位实时研究钙钛矿太阳能电池在特定环境（光、热、湿度）条件下工作时的钙钛矿薄膜微结构、纳米形貌的演化与电池各个光伏参数(转换效率、开路电压、短路电流、填充因子)衰减的关联，并辅以其他结构、形貌、电子结构表征技术，实现全方位动态研究，得到钙钛矿太阳能电池环境稳定性降低的相关机制。此项研究将为解决和提高器件的环境稳定性提供有力的科学基础和依据。

环境湿度对有机-无机杂化钙钛矿薄膜太阳能电池稳定性有着相当重要的影响，研究在湿度环境下钙钛矿薄膜微结构的演化将有助于揭示湿度导致的器件性能衰减的微观机制。本项目基于上海光源X射线衍射线站，建立了一套湿度可调可控的实验装置用以采用同步辐射GIXRD原位实时观测湿度环境下钙钛矿薄膜的微结构演化。同步辐射原位实验观测很好的揭示了器件性能与钙钛矿薄膜形貌以及微结构演化的密切关联，将为理解有机-无机杂化的钙钛矿薄膜的降解微观机制提供实验依据和指导。主要研究内容和重要结果如下：.（1）在相对湿度为602%的环境中，采用原位同步辐射GIXRD首次发现在钙钛矿薄膜暴露湿度环境的最初阶段随着钙钛矿晶体结构的减少和结晶性降低逐渐出现了中间相结构，应该是来源于部分钙钛矿晶体结构的逐渐分解所形成的钙钛矿多相结构；常规的表征也表明经环境湿度处理后的薄膜钙钛矿结晶度的降低和形貌的恶化，而太阳能电池测试表明环境湿度处理降低了器件的性能。.（2）采用同步辐射掠入射X射线衍射（GIXRD）原位实时观测了钙钛矿薄膜整个退火过程中的微结构演化，即从前驱体结构到高度有序的钙钛矿晶体结构的逐步转变过程，特别是我们首次观察到钙钛矿晶体的重结晶过程，有助于增强最终的钙钛矿薄膜的结晶和晶粒堆积的择优取向。.（3）设计了一种红色碳量子点（RCQs）掺杂低温溶液加工的半导体氧化物传输层SnO2，使SnO2的电子迁移率增加到1.73 × 10−2 cm2 V−1 s−1，所得迁移率是改性SnO2的电子迁移率已报道的最高值之一，器件效率达22.77%，处于国际领先水平，相关成果发表在国际著名期刊Advanced Materials（2019, 1906347）上。.（4）通过在钙钛矿前驱体中引入富勒烯衍生物C-PCBOD，实现了钙钛矿晶粒间缺陷的钝化，制备出有史以来柔性钙钛矿太阳能电池最高的功率转换效率。基于同步辐射原位技术揭示出器件高效稳定的物理机制和关键工艺参数，有助于大面积柔性器件产业化发展。相关工作发表在国际权威期刊Advanced Materials（2019, 1901519）上。.本项目基于同步辐射技术发展了系列的原位装置，开展了薄膜制备工艺优化、界面钝化处理、生长界面调控和湿度环境影响等各方面工作，揭示出薄膜微结构与器件之间的构效关系，具有重要的科学意义和应用价值。