Solution-processed intermediate-band solar cells with lead sulfide quantum dots and lead halide perovskites

Abstract

The intermediate-band solar cell (IBSC) with quantum dots and a bulk semiconductor matrix has potential for high power conversion efficiency, exceeding the Shockley-Queisser limit. However, the IBSCs reported to date have been fabricated only by dry process and their efficiencies are limited, because their photo-absorption layers have low particle density of quantum dots, defects due to lattice strain, and low bandgap energy of bulk semiconductors. Here we present solution-processed IBSCs containing photo-absorption layers where lead sulfide quantum dots are densely dispersed in methylammonium lead bromide perovskite matrices with a high bandgap energy of 2.3\u2009eV under undistorted conditions. We confirm that the present IBSCs exhibit two-step photon absorption via intermediate-band at room temperature by inter-subband photocurrent spectroscopy.Intermediate-band solar cell presents a possible route to break the Shockley-Queisser limit but the fabrication has been difficult. Here Hosokawa et al. exhibit working cells at room temperature in solution processed quantum dot-perovskite system with carefully designed miscibility and energy levels.