Efficient and stable carbon-based CsPbBr<sub>3</sub> solar cells added with PEABr additive
Authors: Zhong Ting-Ting , Zhang Chen , Shindume Lomboleni Hamukwaya , Xu Wang-Shu , Tang Kun-Peng , Xu Xiang , Sun Wen-Tian , Hao Hui-Ying , Dong Jing-Jing , Liu Hao , Xing Jie ,   School of Science, China University of Geosciences (Beijing), Beijing 100083, China
Published: January 2022

<sec>In recent years, organic-inorganic hybrid perovskite solar cells have become a research hotspot in the photovoltaic field because of their excellent power conversion efficiency. However, this hybrid perovskite material's intrinsic instability and the harsh preparation environment limit its further commercial application. All-inorganic CsPbBr<sub>3</sub> perovskite materials have attracted much attention because of their good stability, low cost and can be prepared in an atmospheric environment, showing great application potential. The controllable preparation and growth kinetics of CsPbBr<sub>3</sub> materials need to be further studied, and the conversion efficiency of photovoltaic devices is still low. Considering the instability caused by traditional organic hole transport materials and their high preparation cost, this work focuses on the systematical studies of CsPbBr<sub>3</sub> all-inorganic perovskite cells without a hole transport layer. Growth kinetics material of CsPbBr<sub>3</sub> is controlled by adding 2-phenylethylamine bromide to precursor solution<sub>.</sub> The main research contents and results are described as follows.</sec><sec>Based on multi-step spin-coating preparation of CsPbBr<sub>3</sub> perovskite films, the perovskite cell preparation method is studied, and the critical process parameters including the spin-coating PbBr<sub>2</sub>, amount and number of spin-coating of CsBr, substrate preheating temperature, and the annealing temperature, are optimized. The optimization tests show that the optimal spin-coating of CsBr is obtained by being optimized five times and the spin-coating PbBr<sub>2</sub> is conducted in the atmospheric environment. The optimal preheating temperature of the substrate is 80 ℃, and the optimal annealing temperature is 100 ℃. The perovskite films prepared under this condition are compact, each with a continuous high phase purity and good crystallization performance.</sec><sec>The PbBr<sub>2</sub> in DMF is first adopted and the 2-phenylethylamine bromide (PEABr) solution is added to regulate the CsPbBr<sub>3</sub> crystalline quality of the film. The effects of PEABr on the perovskite crystallization process and device performance are systematically investigated. The results show that the introduction of PEABr can effectively optimize the CsPbBr<sub>3</sub>. The crystalline properties of the two-dimensional perovskite materials can improve the grain boundaries and improve their transport properties. The prepared perovskite solar cell with PEABr shows the highest power conversion efficiency of 8.25%, and it can maintain the efficiency of more than 90% when being stored for 1500 h under the condition of no encapsulation. Finally, stable, efficient and low-cost all-inorganic CsPbBr<sub>3</sub> solar cells without a hole layer are obtained.</sec>