Prof. Nam-Gyu PARK, Self-formed grain boundary healing layer for highly efficient perovskite solar cells
- Engineering
- Hit6890
- 2016-06-23
Self-formed grain boundary healing layer
for highly efficient CH3 NH3 PbI3 pervovskite solar cells
Dae-Yong Son, Jin-Wook Lee, Yung Ji Choi, In-Hyuk Jang, Seonhee Lee, Pil J. Yoo,
Hyungjung Shin, Namyoung Ahn, Mansoon Choi, Dongho Kim, Nam-Gyu Park
Nature Energy 1, Article
Published online: 20 June 2016
Abstract
Perovskite solar cells have attracted significant research efforts due to their remarkable performance, with certified power conversion efficiency now reaching 22%. Solution-processed perovskite thin films are polycrystalline, and grain boundaries are thought to be responsible for causing recombination and trapping of charge carriers. Here we report an effective and reproducible way of treating grain boundaries in CH3NH3PbI3 films deposited by means of a Lewis acid–base adduct approach. We show by high-resolution transmission electron microscopy lattice images that adding 6 mol% excess CH3NH3I to the precursor solution resulted in a CH3NH3I layer forming at the grain boundaries. This layer is responsible for suppressing non-radiative recombination and improving hole and electron extraction at the grain boundaries by forming highly ionic-conducting pathways. We report an average power conversion efficiency of 20.1% over 50 cells (best cell at 20.4%) together with significantly reduced current–voltage hysteresis achieved by this grain boundary healing process.