Highly Efficient Aqueous‐Processed Hybrid Solar Cells: Control Depletion Region and Improve Carrier Extraction

Environmental friendly aqueous‐processed solar cells have become one of the most promising candidates for the next‐generation photovoltaic devices. Researchers have made lots of progress in designing active materials with novel structures, manipulating the defects in active materials, optimizing device architecture, etc. However, it has long been a challenge to control the width of the depletion region and enhance carrier extraction ability. Fabrication of a thick bulk heterojunction (BHJ) film is an effective strategy to address these issues but difficult to realize. Herein, the thicker BHJ film of ZnO:CdTe is successfully fabricated and incorporated into CdTe‐poly(p‐phenylenevinylene) hybrid solar cells. As expected, this BHJ film enhances light absorption, extends the width of the depletion region, prolongs carrier lifetime, and promotes carrier extraction ability. Moreover, the electron transport layer of sol–gel ZnO with excellent transmittance and electrical conductivity boosts electron generation, transport, and injection, which further improves the device performance. As a result, the highest short current density (Jsc) of 19.5 mA cm−2, power conversion efficiency of 6.51%, and the widest depletion region (177 nm) are obtained in aqueous‐processed hybrid solar cells. A thicker bulk heterojunction film is successfully fabricated leading to generation of more carriers, extendsion of depleted region width, prolonged carrier lifetime, and improved carrier extraction efficiency. The highest short current density of 19.5 mA cm−2, power conversion efficiency of 6.51% and the widest depletion region (177 nm) are obtained based on aqueous‐processed hybrid solar cells.