Journal Article

Light-induced lattice expansion leads to high-efficiency perovskite solar cells

Durand, Olivier, Even, Jacky, Mohite, Aditya D., Verduzco, Rafael, Kanatzidis, Mercouri G., Ajayan, Pulickel M., Alam, Muhammad Ashraf, Asadpour, Reza, Stoumpos, Constantinos C., Blancon, Jean-Christophe, Tretiak, Sergei, Strzalka, Joseph W., Nie, Wanyi, Chen, Bo, Tsai, Hsinhan

2018

Overview

Ion migration in organic-inorganic perovskite solar cells limits device stability and performance. Tsai et al. found that a cesium-doped lead triiodide perovskite with mixed organic cations underwent a uniform lattice expansion after 180 min of exposure at 1 sun of illumination. This structural change reduced the energy barriers for charge carriers at the contacts of solar cells. The resulting increase in power conversion efficiency from 18.5 to 20.5% was maintained for more than 1500 hours of illumination. Science , this issue p. 67 Light-induced lattice expansion improves crystallinity and relaxes lattice strain in organic-inorganic perovskite films. Light-induced structural dynamics plays a vital role in the physical properties, device performance, and stability of hybrid perovskite–based optoelectronic devices. We report that continuous light illumination leads to a uniform lattice expansion in hybrid perovskite thin films, which is critical for obtaining high-efficiency photovoltaic devices. Correlated, in situ structural and device characterizations reveal that light-induced lattice expansion benefits the performances of a mixed-cation pure-halide planar device, boosting the power conversion efficiency from 18.5 to 20.5%. The lattice expansion leads to the relaxation of local lattice strain, which lowers the energetic barriers at the perovskite-contact interfaces, thus improving the open circuit voltage and fill factor. The light-induced lattice expansion did not compromise the stability of these high-efficiency photovoltaic devices under continuous operation at full-spectrum 1-sun (100 milliwatts per square centimeter) illumination for more than 1500 hours.

• Publisher: The American Association for the Advancement of Science,American Association for the Advancement of Science (AAAS),AAAS
• Subject: Cations / Cesium / Chemical Sciences / Current carriers / Efficiency / Energy charge / Energy conversion efficiency / Illumination / Interfaces / Lattice strain / Light / Open circuit voltage / Optoelectronic devices / Perovskites / Photovoltaic cells / Photovoltaics / Physical properties / Physics / Solar cells / SOLAR ENERGY / Stability / Thin films