Low-Temperature Annealed Perovskite Films: A Trade-Off between Fast and Retarded Crystallization via Solvent Engineering

Currently, in the field of photovoltaics, researchers are working hard to produce efficient, stable, and commercially feasible devices. The prime objective behind the innovation of any photovoltaic device is to yield more energy with easy manufacture and less process cost. Perovskite solar cells (PSCs) are prominent in the field of photovoltaics, owing to its low material cost, simple fabrication process, and ideal optoelectronic properties. Despite rapid augmentation in progress of PSCs, it is still a bottleneck to produce a high-quality perovskite layer at low temperatures in a short time. Herein, a facile solvent engineering technique is used to produce a high-quality perovskite layer at 50 °C in just 30 min. We employed solvent coordination strength to form the intermediate state as well as their sensitive behavior against antisolvent to establish a trade-off between fast and retarded crystallization. Dimethylsulphoxide (DMSO), a traditional co-solvent is used as an additive instead of co-solvent; in contrast, mixed 1-methyl-2-pyrrolidinone (NMP) and dimethylacetamide are employed as principal solvents for perovskite precursors. Different volume ratios of DMSO as a fraction of NMP are added to examine the evolution of the perovskite layer at low temperatures. It is noted that the mixed solvent with 30% DMSO shows a pin-hole free, uniform, and compact layer with a strong absorption spectrum. Promisingly, the corresponding device with 30% DMSO shows a high efficiency of 18.19%, which is even comparable to traditionally high-temperature annealed PSCs. These findings may provide a way to produce low-temperature annealed, high-quality perovskite films and subsequently facilitate the production of cost-effective and efficient devices.