铯铅卤无机钙钛矿(CsPbX₃)因其优异的光电性能和良好的热稳定性而备受关注。其中，混合卤素CsPbI₂Br兼具CsPbI₃和CsPbBr₃的优点：同时拥有较为合适的禁带宽度(1.91 eV)和相对优异的室温相稳定性，是制备高效稳定钙钛矿电池较为理想的吸收层材料。然而，传统溶液法制备的CsPbI₂Br无机钙钛矿薄膜仍存在覆盖率低、厚度薄，晶粒小，相纯度不高等缺点，限制了电池性能和稳定性的进一步提高。针对当前溶液法在制备高效稳定CsPbI₂Br光伏器件方面所面临的困难，本论文基于反溶剂工程和添加剂工程发展了高效、可控制备高质量CsPbI₂Br薄膜的一步和多步溶液法，系统研究了不同制备工艺对CsPbI₂Br吸收层的表面覆盖度、形貌、结品性、相纯度和光吸收性能的影响。在此基础上，通过采用稳定性好、低成本的碳电极取代传统的有机空穴传输层以及贵金属电极，组装出具有高转换效率、同时能够长期稳定工作的CsPbI₂Br全无机钙钛矿太阳能电池。论文取得了以下主要研究结果： 1.基于传统的一步溶液法，在不同退火温度下制备了CsPbI₂Br无机钙钛矿薄膜。研究发现，具有光伏特性的α-CsPbI₂Br钙钛矿的相形成温度需要在240℃以上，并且所形成钙钛矿相的环境稳定性随着退火温度的升高而改善。在一定范围内升高退火温度也利于CsPbI₂Br薄膜晶粒尺寸的增大和结晶性的提升，但过高的退火温度会破坏CsPbI₂Br的薄膜质量。退火温度为340℃时所制备的α-CsPbI₂Br薄膜结晶质量高且相稳定性好，但其表面覆盖度仍有待提高。基于碳电极构建的无空穴传输层CsPbI₂Br电池初步实现4.89％的转换效率。 2.在传统一步法的基础上，通过引入反溶剂工程来辅助改善CsPbI₂Br薄膜的成核结晶过程。采用乙酸乙酯(EA)绿色溶剂代替氯苯(CB)有毒溶剂作为新型反溶剂，详细研究了传统一步法以及不同反溶剂处理对CsPbI₂Br无机钙钛矿成膜质量以及器件性能的影响。结果表明，相对于CB反溶剂和传统一步法，利用EA反溶剂辅助结晶过程可以有效改善CsPbI₂Br薄膜的覆盖度和致密性，增加晶粒尺寸，降低晶界密度。基于EA反溶剂法制备的碳电极基CsPbI₂Br全无机钙钛矿电池实现了10.0％的光电转换效率，并表现出较好的器件稳定性，明显优于传统一步法和CB反溶剂法制备的钙钛矿电池性能。 3.基于反溶剂工程，提出了一种绿色反溶剂辅助多步沉积的新方法，用于制备相纯度高且成膜质量好的CsPbI₂Br无机钙钛矿薄膜。通过在PbI₂前驱体成膜过程中引入CB反溶剂处理，成功地诱导了PbI₂(DMSO)中间相的快速成核析出以及多孔结构的形成；疏松的多孔结构对CsBr分子的扩散，以及PbI₂与CsBr后退火充分反应生成钙钛矿有积极的促进作用。通过调节后续CsBr的沉积循环次数实现了CsPbI₂Br薄膜结晶质量、晶粒大小以及相成分的可控调节。进一步研究表明，不同性质的反溶剂处理对中间相薄膜的形态结构有重要影响，采用经绿色反溶剂乙醇(EtOH)处理得到的孔隙率高、晶粒取向随机的PbI₂薄膜。在优化的CsBr沉积条件下，基于乙醇反溶剂辅助多步沉积法制备出了钙钛矿相纯度高、结晶性好、晶粒尺寸及厚度增大的CsPbI₂Br薄膜，所构建的碳基全无机钙钛矿电池最佳转换效率达10.21％，并表现出良好的长期稳定性。 4.将强极性溶剂DMF作为添加剂引入到CsBr甲醇溶液中，通过多步沉积过程制备CsPbI₂Br无机钙钛矿薄膜，详细研究了DMF添加量对CsPbI₂Br薄膜成膜质量、相成分以及器件性能的影响。结果表明，适量的DMF添加剂能够在前驱体膜中引发适度的溶解再结晶过程，促进CsBr的内扩散及其与PbI₂薄膜之间的充分反应，从而对CsPbI₂Br薄膜的结晶动力学过程形成有效调控。DMF添加量为1.5％时成膜效果最优，可获得杂相少、结晶性高、晶粒尺寸可达微米量级、且晶界垂直于基底的CsPbI₂Br薄膜，上述薄膜特性在改善载流子传输和降低复合损失方面起到了重要作用。所构建的碳基CsPbI₂Br全无机钙钛矿电池达到了9.56％的最佳转换效率。 关键词：CsPbI₂Br，溶剂工程，成膜质量，碳电极，全无机钙钛矿电池

 Cesium lead halide inorganic perovskites (CsPbX₃) have received considerable attention owing to their excellent optoelectronic properties and super thermal stability. Among them, mixed-halide CsPbI₂Br combines merits of CsPbI₃ and CsPbBr₃, i.e. a reasonable band gap (1.91 eV) and much improved ambient phase stability, and has been considered as the ideal absorber for fabricating efficient and stable perovskite solar cells (PSCs). However, traditional solution-processed CsPbI₂Br inorganic perovskite films still suffer from many shortcomings, such as poor coverage, thin thickness, fine grains and low phase purity, which impede the further improvement of device performance and stability. In order to solve the current problems encountered in the preparation of highly efficient and stable CsPbI₂Br PSCs by the solution methods, this work focuses on the fabrication of high-quality CsPbI₂Br film via the effective and controllable one-step and multi-step solution methods based on the anti-solvent engineering and additive engineering. The influences of different preparation processes on the surface coverage, morphology, crystallinity, phase purity, and light absorption properties of the CsPbI₂Br absorbers were systematically investigated. Furthermore, by using stable and low-cost carbon electrode to replace the conventional organic hole transport materials (HTMs) and the noble metal electrode, CsPbI₂Br all-inorganic PSCs with high power conversion efficiencies (PCEs) and long-term stability were developed. The main results are summarized as follows: 1.CsPbI₂Br inorganic perovskite films were prepared at different annealing temperatures based on the traditional one-step solution method. It is found that the phase formation of α-CsPbI₂Br perovskite with photovoltaic activity occurs at temperatures above 240 ℃. and the ambient phase stability of α-CsPbI₂Br improves with the increase of annealing temperature. Raising the annealing temperature in a proper range can also enlarge the grain size and improve crystallinity, while over high annealing temperature could deteriorate α-CsPbI₂Br film quality. High-crystalline and phase-stable α-CsPbI₂Br films can be obtained at the annealing temperature of 340 ℃. However, the surface coverage of these films is still poor and needs further improvement. 4.89 % PCE was initially achieved on a carbon-based HTM-free CsPbI₂Br PSCs. 2.Anti-solvent engineering was introduced to improve the nucleation and crystallization processes of CsPbI₂Br films on the basis of traditional one-step solution method. Ethyl acetate (EA) was adopted as a novel and green anti-solvent to replace toxic chlorobenzene (CB). The influences of traditional one-step process and different anti-solvent treatments on the film quality and device performance were studied in detail. The results indicate that compared with conventional one-step and CB antisolvent treatment processes, the utilization of EA anti-solvent assisted crystallization can effectively improve the coverage and compactness of CsPbI₂Br films, enlarge their grain sizes and decrease the grain boundary density. Carbon-based CsPbI₂Br allinorganic PSCs prepared via EA anti-solvent engineering method achieve an exceptional PCE of 10.0 % and show significant long-term stability, which is obviously superior to the traditional one-step and CB anti-solvent processed PSCs. 3.Based on the anti-solvent engineering, a new green anti-solvent assisted multi-step deposition method was proposed to prepare pure-phase and high-quality CsPbI₂Br inorganic perovskite films. Introducing CB anti-solvent in the PbI₂ precursor filming processes successfully induces the fast precipitation of PbI₂(DMSO) intermediate complexes and the formation of a porous film structure. Loose and porous PbI₂ film could effectively facilitate the thorough diffusion of CsBr molecules and the complete annealing reaction between PbI₂ and CsBr. The crystallinity, grain sizes and phase composition of CsPbI₂Br films can be well controlled by adjusting the subsequent CsBr deposition cycles. Further studies indicate that treatments from different anti-solvents lead to various morphologies of PbI₂ intermediate film. PbI₂ film with high porosity and randomized grain orientation can be achieved by utilizing green ethanol (EtOH) anti-solvent treatment. With the optimal CsBr deposition conditions, highly pure-phase and thick CsPbI₂Br films with large grain sizes and high crystallinity were obtained via EtOH anti-solvent assisted multi-step deposition method. Finally, carbon-based all-inorganic PSCs fabricated from these high-quality CsPbI₂Br films achieve a champion efficiency of 10.21%, and show a promising long-term stability. 4.The polar solvent DMF was introduced into CsBr/MeOH solution as an additive to prepare CsPbI₂Br inorganic perovskite films with a multi-step deposition method. The influences of DMF amount on the film quality, phase composition and device performance were investigated in detail. It is shown that a proper amount of DMF will induce dissolution-recrystallization process with an appropriate degree in the precursor films, and promote the internal diffusion of CsBr and the sufficient reaction between CsBr and PbI₂, thus effectively modulating the crystallization kinetics of CsPbI₂Br perovskite. CsPbI₂Br films with features of few impurities, high crystallinity. micronsized grains, and vertically aligned grain boundaries, which are important to improve carrier transport and decrease recombination losses, can be obtained at the optimal DMF content of 1.5 %. The fabricated carbon-based all-inorganic PSCs demonstrates a remarkably high PCE of 9.56 %. Key Words: CsPbI₂Br, Solvent engineering, Film quality, Carbon electrode, Allinorganic perovskite solar cells