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 eV 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.
Highlights
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
The IB corresponds to the conduction band (CB) of QDs3,4
In order to obtain a photo-absorption layer with the Quantum dots (QDs) particle density of not less than 1 × 1012 cm−2 per layer which is the highest density achieved by the molecular beam epitaxy (MBE) method[28], the PbS QDs of 11 volume% or more were hybridized with the perovskite matrix (Fig. 1b)
Summary
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. 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. Quantum dots (QDs) incorporated into the bulk matrix have been considered as one of the most promising candidates to realize the IBSCs5–11 Such IBSCs have been fabricated only by dry process such as the molecular beam epitaxy (MBE) and metal organic chemical vapor deposition (MOCVD). We create IBSCs containing photo-absorption layers where QDs are densely dispersed in a bulk matrix with a high EBG under undistorted conditions by the solution process. The IBSCs are confirmed to exhibit TSPA via IB at room temperature by inter-subband photocurrent spectroscopy
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