Mesoscopic CH3NH3PbI3 perovskite solar cells using TiO2 inverse opal electron-conducting scaffolds†
One of the current needs of applications involving perovskite solar cells is reducing the hysteresis of the current density–voltage response with respect to the scan direction and rate. This reduction enables high and stable power conversion efficiency (η). For this purpose, a mesoscopic electron conductor with low trap density and high electron conductivity that balances charge flux is highly desirable. In the present study, we prepared a mesoscopic inverse opal (meso-IO) film with a three-dimensionally interconnected porous structure and used it as an electron-conducting scaffold for perovskite solar cells. We controlled the thickness of the meso-IO scaffold and determined its effect on the cells' photovoltaic performance. Solar cells using the 600 nm thick meso-IO scaffold exhibited a maximum η of 17.1%, no hysteresis of photocurrent density between forward and reverse scan directions, as well as hysteresis of η of only 0.5% p.