The organic-inorganic hybrid halides perovskite solar cells have been improved to the certificated efficiency of 22.1% recently and the coming question is how to easily get the high quality perovskite films to meet the requirement for its future real applications.
The traditional solution processing method for the synthesis the perovskite material is generally using PbI
2 (or PbCl
2) and MAI as the precursors, which is then coated onto a substrate. Heat is applied to remove the solvent, to leave some un-defined intermediate adducts and then transforming desired perovskite crystals on the substrate. The reaction occurring during the heating treatment is too complicated and it may bring the difficulty to exactly control the quality of the perovskite films.
Researchers in Qingdao Institute of Bioenergy and Bioprocess Technology (QIBEBT), Chinese Academy of Sciences, developed a new solid-gas reaction method to fabricate high-quality perovskite films recently.
Prof. Shuping PANG’s group has discovered that the magical phenomena of methylammonium lead trihalide perovskite could reversibly uptake and degas methylammonium gas upon controlling its partial pressure, which is very promising to scale up the fabrication of perovskite thin films (
Angew. Chem. Int. Ed., 2015, 54: 9705).
Based on this work, Prof. PANG’s group, cooperated with Prof. Nitin P. PADTURE at Brown University and Dr. Kai ZHU at National Renewable Energy Laboratory (NREL), further modified the synthetic route of perovskite material. Instead of traditional PbI
2/MAI reaction system, the use of HPbI
3/MA reaction system first realized the fabrication of perovskite materials through low temperature solid-gas reaction. The use of HPbI
3 as precursor material simplified manufacturing process by synchronizing the synthesis and healing process of perovskite thin film (Figure 1). As this novel reaction system tends not to break the PbI
6 octahedral structure, similar to the topological changes of crystal structure, resulting in an extremely high improvement of the film quality (
J. Am. Chem. Soc., 2016, 138: 750). Recently, the international team has further developed this method to converts one type of perovskite into another. This technique is simple, versatile, and has the potential to be scaled up, which overcomes a real bottleneck in perovskite research at the moment (
J. Am. Chem. Soc., 2016, DOI:10.1021/jacs.6b02787).
These work was published recently in the
Journal of the American Chemical Society.
Figure 1. Scheme of a nonsalt-based precursor pair (inorganic HPbI3 solid and organic CH3NH2 gas) for the deposition of uniform CH3NH3PbI3 perovskite thin films. (Image by QIBEBT)
