Unveiling the Effects of Hydrolysis‐Derived DMAI/DMAPbIx Intermediate Compound on the Performance of CsPbI3 Solar Cells

• Published in: Advanced science Vol. 7; no. 9
• Main Authors: Bian, Hui, Wang, Haoran, Li, Zhizai, Zhou, Faguang, Xu, Youkui, Zhang, Hong, Wang, Qian, Ding, Liming, Liu, Shengzhong (Frank), Jin, Zhiwen
• Format: Journal Article
• Language: English
• Published: Hoboken John Wiley and Sons Inc 01-05-2020; Wiley
• Subjects: Communication; Communications; CsPbI3; DMAI; DMAPbIx; intermediate compounds; solar cells
• ISSN: 2198-3844; 2198-3844
• DOI: 10.1002/advs.201902868

Introducing hydroiodic acid (HI) as a hydrolysis‐derived precursor of the intermediate compounds has become an increasingly important issue for fabricating high quality and stable CsPbI3 perovskite solar cells (PSCs). However, the materials composition of the intermediate compounds and their effects on the device performance remain unclear. Here, a series of high‐quality intermediate compounds are prepared and it is shown that they consist of DMAI/DMAPbIx. Further characterization of the products show that the main component of this system is still CsPbI3. Most of the dimethylammonium (DMA+) organic component is lost during annealing. Only an ultrasmall amount of DMA+ is doped into the CsPbI3 and its structure is stabilized. Meanwhile, excessive DMA+ forms Lewis acid–base adducts and interactions with Pb2+ on the CsPbI3 surface. This process passivates the CsPbI3 film and decreases the recombination rate. Finally, CsPbI3 film is fabricated with high crystalline, uniform morphology, and excellent stability. Its corresponding PSC exhibits stable property and improved power conversion efficiency (PCE) up to 17.3%.
This work mainly focuses on materials composition and working mechanism of the hydroiodic acid (HI) hydrolysis‐derived intermediate compound DMAI/DMAPbIx. Importantly, the main component of the CsPbI3 film prepared by such precursor is proved to be still inorganic. Finally, the optimized CsPbI3 film–based device shows significantly enhanced stability in ambient environment with a high power conversion efficiency of 17.32%.