High-performance narrowed-bandgap PbS quantum dot infrared solar cell by advanced bilayer hole transport layer

A facile and novel bilayer HTL is demonstrated to enhance the performance of PbS QDs photovoltaics. • The advanced bilayer HTL shows “crack-healing” effect while maintains well -matched energy levels with photoactive layer. • The advanced bilayer HTL exhibits remarkably suppressed trap states and high film quality. • As results, high-performance narrowed-bandgap PbS QDs IR cells are achieved with a champion IR PCE of 1.52%. PbS quantum dots (QDs) infrared (IR) solar cells, able to convert low-energy IR photons into electron-hole pairs, are hopeful photovoltaic devices because it broadens the utilization range of the solar spectrum to IR region. Currently, PbS infrared solar cells usually apply small-sized PbS QDs treated with 1,2-ethanedithiol as hole transport layer (HTL) by solid-state ligand exchange (SSLE) method. However, cracks are prone to generate in HTL due to volume shrinkage in SSLE process, resulting in deterioration of devices performance. Here, a facile and novel bilayer PbS QDs HTL is demonstrated by applying QDs synthesized via different methods to form bilayer structures. It is discovered that bilayer structure can “healing” the film cracks and reduce trap states, which is contributed to the carrier separation and extraction in devices. Meanwhile, the advanced bilayer HTL maintains the well-match energy levels with the narrowed-bandgap PbS QDs photoactive layer. As results, superior average AM1.5 PCE of 10.45% (the champion device achieved 12.27%) and average infrared PCE (IR PCE) of 1.24% (the champion device achieved 1.52%) were obtained in devices with the bilayer HTL, demonstrating a facile and reliable approach to enhance the performance of optoelectronic devices. A facile and novel bilayer HTL is demonstrated to improve device performance. Download: Download high-res image (338KB) Download: Download full-size image