Study on the Ambient Temperature As an Important but Easily Neglected Factor in the Process of Preparing Photovoltaic All-Inorganic CsPbIBr2 Perovskite Film by the Elegant Solvent-Controlled Growth Strategy

All-inorganic CsPbIBr2 perovskite has received extensive attention in the field of solar cells due to its good wet and thermal stability as well as a moderate band gap. In the preparation of CsPbIBr2 film by one-step spin-coating method, the amount of dimethyl sulfoxide solvent remaining in the precursor film has a great influence on the process of film growth. Therefore, it is necessary to ensure that an appropriate amount of solvent exists in the precursor film before annealing. Herein, we adopted the solvent-controlled growth (SCG) strategy, that is, standing by the precursor films in the nitrogen glovebox for a period of time before annealing, to make sure that excess solvent can be evaporated from the precursor film. In this work, we found that the ambient temperature is an important but easily neglected factor in the process of preparing CsPbIBr2 film by the SCG strategy. When the ambient temperature is 20 degrees C, SCG treatment is required to obtain a flat and dense CsPbIBr2 film. However, SCG treatment is not essential at 30 degrees C. The ambient temperature has an impact on the evaporation rate of the solvent in the precursor film, and thus affects the effect of the SCG strategy. This work highlights that, when preparing CsPbIBr2 film by a one-step spin-coating method, in order to obtain a high-quality CsPbIBr2 film, the influence of ambient temperature on solvent-controlled growth strategy should be considered.