Qingdao Energy Institute et al. proposed a new technology for repairing formamidine-based perovskite thin films after ammonia gas

Perovskite solar cells are an emerging photovoltaic technology.
After development, their photoelectric conversion efficiency is comparable to that of silicon cells.
It is considered to be a new generation of solar cell technology with considerable commercialization prospects
.
How to easily fabricate high-quality perovskite thin films on a large scale is one of the challenges in the commercialization process
.

Qingdao Institute of Bioenergy and Processes, Chinese Academy of Sciences is one of the earliest units engaged in the research of formamidine-based perovskite materials.
In response to its large-area film formation problem, the Solid State Energy System Technology Center and Qingdao University of Science and Technology have revealed that in aliphatic amine environment Based on the potential chemical side reactions of perovskite in the system of methylamine and formamidine, it is further proposed that ammonia gas is used for post-repair of formamidine-based perovskite films
.
The related results were published in Nature Communications
.

The researchers focused on exploring the existence of a series of side reactions such as addition and elimination reaction (also known as transimine reaction), ion exchange reaction and hydrolysis reaction of formamidine iodide in the amine gas environment
.
It was found that the main product of the transimmination reaction between the formamidine cation and aliphatic amine was ammonia
.
Therefore, choosing ammonia gas as the post-repair gas can effectively avoid the influence on the material composition
.
The research achieved the efficient repair of the formamidinium-based perovskite thin film through further regulation of temperature and pressure, which significantly improved the uniformity and consistency of the thin film
.
The perovskite solar cells prepared by this repair technology achieved the highest photoelectric conversion efficiency of 23.
21%, and the module efficiency exceeded 20%
.
This research builds the chemical basis for the technology of repairing perovskite thin films after ammonia gas, and the process is compatible with current commercial coating processes and is easy to scale up, which is expected to accelerate the industrialization of perovskite solar cells process
.

The research work is supported by the Youth Innovation Promotion Association of the Chinese Academy of Sciences and the Shandong Energy Research Institute
.

Repair Mechanism of Formamidinium-Based Perovskite Thin Films