钙钛矿结构CH3NH3PbI3晶体的空间限域合成及其多形变太阳能电池的研究

Perovskite solar cells prepared by the two-step coating method have realized an efficiency as high as 19.3%, they have been considered as one of the research hotspots for markedly reducing the cost of photovoltaic conversion. However, the perovskite CH3NH3PbI3 material prepared by the two-step coating method display single cuboid-like crystals and limitations in reducting crystal size and charge recombination. Moreover, the rigid perovskite solar cells from conductive glass have disadvantages in high weight, ffrangibility, and unbendability, demonstrating an unavailability in curved fields. By addressing these issues, one of the solutions to this impasse is to develop multideformational perovskite solar cells with high efficiency and to realize polymorphic and large-sized CH3NH3PbI3 crystals. In the current proposal, we launch a strategy of assembling bendable, stretchable, compressible, and twistable perovsikite solar cells using hydrophobic hydrogels having three-dimensional frameworks as matrices by a sequent absorption technique. The focus of the research is to demonstrate the dependence of growth process of perovskite-structured CH3NH3PbI3 on gel structure, to reveal the spatial confinement growth mechanism, and to study the evolution law of cell performances and dynamical structures. After optimazing the synthesis conditions, the perovskite solar cells with efficiencies higher than 8% are expected to be realized.

采用液相两步法制备的钙钛矿太阳能电池已实现了19.3%的光电转换效率，成为大幅度降低光伏发电成本的研究热点之一。然而，液相法制备的钙钛矿型CH3NH3PbI3晶体具有单一的立方体形状，而且在增大晶体尺寸和减小电荷复合率等方面具有局限性。此外，基于导电玻璃的刚性钙钛矿太阳能具有质重、易碎、无法弯曲等缺陷，在特殊曲面领域难以应用。开发一种多形变钙钛矿太阳能电池并实现CH3NH3PbI3晶体的形貌多元化和大尺寸有望解决上述问题，并提高电池的光电转换效率。本项目拟采用具有三维网络结构的疏水凝胶为基体，采用分级吸附的方法组装可弯曲、可拉伸、可压缩、可扭曲的钙钛矿太阳能电池并实现CH3NH3PbI3晶体的空间限域生长。考察凝胶结构对钙钛矿材料合成的影响及其空间限域生长机理，研究多形变太阳能电池的电池性能和动态结构衍变规律。通过优化技术路线，预计可组装光电转换效率超过8％的多种形变钙钛矿太阳能电池。

自2009年以来，被认为有望大幅降低光伏发电成本的钙钛矿太阳能电池（简称PSC）迅速发展，光电转换效率也由最初的3.8%提升至23%以上，并很快成为薄膜太阳电池研究的热点之一。钙钛矿吸光材料的制备技术和器件柔性化是提高光电转换效率和拓展应用领域的关键。本项目采用具三维网络结构的疏水凝胶材料为基体，通过分级吸附的方法，实现可弯曲、可拉伸、可压缩、可扭曲n-i-p型PSC的设计，同时研究了CH3NH3PbI3晶体的空间限域生长机理并获得器件光伏性能的衍变规律。主要研究成果包括以下几方面：(1) 通过改变单体、改性剂、交联剂、引发剂、反应温度等实现了凝胶基体的可控制备，优化了凝胶结构和吸附性能。(2) 实现了钙钛矿结构CH3NH3PbI3晶体在三维凝胶内的空间限域生长，研究了CH3NH3PbI3晶体的形貌、尺寸、结晶性对电荷传输路径、电荷复合率以及太阳能电池的光伏性能的影响。(3) 系统研究了钙钛矿太阳能电池的弯曲、扭曲、压缩、拉伸等多形变特性，掌握了光伏性能在形变过程的演变规律并揭示了器件结构、电荷传输等的内在机制。（4）开展了全无机CsPbBr3吸光材料及其太阳电池的拓展性实验，通过开发CsPbBr3的多步液相制备技术并结合界面工程、组分工程、光谱工程等获得了同类电池公开报道最高的10.60%的光电转换效率，不仅提升了器件的环境稳定性，又降低了实际生产难度和成本。通过项目的实施，我们已经完成了所有预期目标，共发表SCI论文40篇，出版专著2部，授权国家发明专利8项，获科研奖励5项。