Material and device design for multijunction perovskite solar cells

A next target in photovoltaic energy conversion can possibly be met by developing perovskite triple or even quadruple junction solar cells. These require developing stable perovskite sub-cells with bandgaps in the range of 1.8 to 2.3 eV, i.e., a range that has not received much attention so far. Guided by photocurrent spectroscopy and absolute photoluminescence spectroscopy, in combination with bulk and interface passivation strategies, tandem and triple junction solar cells with a power-conversion efficiency of 26% have been reached. Photoluminescence of individual sub-cells provides information on the internal voltage in each absorber layer and offers a detailed understanding of the performance-limiting components in the tandem solar cell following prolonged continuous operation.