Abstract
While the development of perovskite-based semitransparent solar cells with competitive levels of transparency and efficiency offer a promising perspective towards building integrated photovoltaics, the color perception of perovskite films is of limited visual aesthetics, compromising their applicability to facades and windows. In the present work, we develop a technique to grow crystalline, ultrathin perovskite films through a solvent-solvent extraction process featuring full crystallization within few seconds at RT and under 45%RH environmental conditions. As a result we obtained the highest combination of efficiency and transparency to date for perovskite solar cells. We further improved the visual aesthetics of our devices by implementing dielectric mirrors. EQE and UV-Vis spectroscopic measurements are performed to fully characterize the device stacks featuring four different dielectric mirror configurations. By customizing the mirror to the near-IR absorption region of the perovskite, we could increase the Jsc by 18.7%, yielding a light blue appearance and showing 31.4% transparency at 3.5% electrical power efficiency. Both, the solar cells and the dielectric mirrors are fully-solution processed under ambient conditions and are easily transferable to roll-to-roll upscaling. Optical simulations support our experimental findings and provide a global perspective emulating full device stack appearance covering all the colors in the visible spectra. Transparency, photocurrent density contribution and chromaticity are finally simulated and analyzed. Based on the detailed analysis, we give an outlook on the performance – color – transparency roadmap for perovskite solar cells.