PbS QDs as Electron Blocking Layer Toward Efficient and Stable Perovskite Solar Cells

Abstract

Colloidal PbS quantum dots (QD), which possess size-tunable bandgap, multiple exciton generation effect, and low-cost synthesis process, are regarded as potential candidates in thin film photovoltaic field. Meanwhile, perovskite solar cells (PSCs) are prospecting photovoltaic devices with high power conversion efficiency (PCE). However, the high-performance PSCs largely rely on expensive and unstable organic hole transporting material (HTM), such as spiro-OMeTAD. Here, we design a new PSC architecture with a perovskite/PbS quantum dots (QDs) heterojunction film, which promotes hole extraction and decreases carrier recombination. By optimizing the concentration of colloidal PbS QDs, a PCE of 11.32% can be achieved, which is far higher than the control HTM-free PSCs (6.96% in PCE). In addition, the device structure exhibits higher stability than the conventional PSCs based on the control one. These findings along with low-temperature fabrication ( <100 °C) offer an alternative route in HTM-free heterojunction structure for low-cost and high-performance flexible PSCs.