A Review on Halide Perovskite Film Formation by Sequential Solution Processing for Solar Cell Applications. Issue 4 (27th November 2019) - Bing, Jueming
Abstract : Perovskite solar cell performance is closely related to the quality of the perovskite absorbing layer which is highly dependent on deposition processes. Sequential process is shown to be effective in fabricating both single‐junction and tandem solar cells delivering comparable efficiencies compared with devices by a single‐step process. Sequence processes exhibit the benefits of controlling crystallization speed, overcoming solvent incompatibility, and greater flexibility. Here, mechanisms of film formation in two common sequential solution processes, namely chemical bath deposition and sequential spin coating, showing that film formation is highly dependent on precursors or deposition conditions, are reviewed. Herein, further review is conducted on how three main strategies improve perovskite crystallization. The first is by PbI2 complex formation or via intramolecular exchange which is shown to result in a better perovskite conversion and a more ordered perovskite growth. The second strategy is by changing the condition of perovskite precursors, e.g., by solvent, cation, halide, and additive engineering. The last strategy is by altering precursor dispensing conditions and adding vapor or solvent annealing, thereby affecting reaction conditions. Many of these strategies are demonstrated to improve perovskite film morphology with reduced defects. Abstract : Herein, a general overview of sequence deposition for perovskite film formation followed by a more focused review on sequence solution processes is provided. Between 2013 and 2019, there were more than 70 studies on perovskite sequential solution processes alone. Key strategies for improving perovskite film quality for improving the performance of associated solar devices are discussed.