A crystalline semiconductor with a perovskite structure is coated with a thin film to create perovskite solar cells (PSCs). Therefore, controlling the crystallization behavior of the thin film to avoid internal defects is crucial for good efficiency.

In particular, depositing a thin film of α-formamidinium lead iodide (FAPbI3) perovskites with fewer defects is essential due to their excellent crystallinity and large grain size.

A research team associated with UNIST revealed a way to surpass the 26% efficiency of perovskite solar cells (PSCs). They revealed a new method and principle for controlling the crystallinity of perovskite photoactive layer semiconductors. They also developed a technology to manufacture highly efficient PSCs.

According to scientists, their method could surpass the efficiency of silicon solar cells.

Using this technique, perovskite solar cells were made with the best efficiency in the world (26.08%), also recognized by the National Renewable Energy Laboratory (25.73%).

Distinguished Professor Sang Il Seok from UNIST’s Department of Energy and Chemical Engineering said: “Alkylammonium chloride (RACI), which is dequantized at the crystallization stage while combining with perovskite components, was used. This optimal combination with Alkyl could also optimally control the solvent volatilization rate during the coating and heat treatment of perovskite precursor solution. This combination made it possible to produce a perovskite thin film that is dense while at the same time making the surface of the thin film extremely flat, and has excellent crystallinity that minimizes internal defects of the crystal.”

Professor Tae Joo Shin, Graduate School of Semiconductor Materials and Devices Engineering at UNIST, said: “This study is very meaningful, as it examines the crystallization process of perovskite with halide anions in real time through Pohang Accelerator Laboratory’s UNIST-PAL Beamline.”

Professor Seok said: “Through this study, perovskite solar cells with an efficiency of more than 26% will soon surpass the efficiency of silicon solar cells. This research is the starting point of the journey to achieve more than 27% efficiency.”

Professor Seok has surpassed the 20% efficiency of PSCs for the first time and holds the world’s best certified efficiency record. In particular, the perovskite heterojunction nip solar cell structure was announced for the first time in the world. Even today, more than 25% of high-efficiency perovskite solar cells have this structure.

Magazine reference:

  1. Park, J., Kim, J., Yun, HS. et al. Controlled growth of perovskite layers with volatile alkylammonium chlorides. Nature (2023). DOI: 10.1038/s41586-023-05825-y