Scientists at UNIST have achieved the world’s highest power conversion efficiency (PCE) record for a perovskite solar cell (PSC) at 25.8%. They created an interlayer between electron-transporting and perovskite layers to minimize interfacial defects.
The high-concentration defects in the interfaces between the perovskite and charge-transporting layers significantly reduce the power conversion efficiency of the devices. Many studies that aimed to reduce these defects mainly focused on surface passivation. Yet, passivating the perovskite surface that interfaces with the electron-transporting layer have been difficult because the surface-treatment agents on the electron-transporting layer may dissolve while coating the perovskite thin film.
Scientists noted, “Alternatively, interfacial defects may not be a concern if a coherent interface could be formed between the electron-transporting and perovskite layers.”
Scientists, in this study, created an interlayer between a SnO2 electron-transporting layer and a halide perovskite light-absorbing layer. Thanks to this interlayer, scientists were able to achieve coupling Cl-bonded SnO2 with a Cl-containing perovskite precursor.
Professor Sang Il Seok in the School of Energy and Chemical Engineering at UNIST said, “This interlayer has atomically coherent features, which enhance charge extraction and transport from the perovskite layer, and fewer interfacial defects.”
“The existence of such a coherent interlayer allowed us to fabricate perovskite solar cells with a power conversion efficiency of 25.8% under standard illumination, adding that unencapsulated devices maintained about 90% of their initial efficiency even after continuous light exposure for 500 hours. They anticipate that such findings provide guidelines for designing defect-minimizing interfaces between metal halide perovskites and electron-transporting layers.”
- Hanul Min, Do Yoon Lee, Junu Kim, et al., “Perovskite solar cells with atomically coherent interlayers on SnO2 electrodes,” Nature (2021). DOI: 10.1038/s41586-021-03964-8