Solution‐Processed CsPbBr3 Quantum Dots/Organic Semiconductor Planar Heterojunctions for High‐Performance Photodetectors

Planar heterojunctions (PHJs) are fundamental building blocks for construction of semiconductor devices. However, fabricating PHJs with solution‐processable semiconductors such as organic semiconductors (OSCs) is a challenge. Herein, utilizing the orthogonal solubility and good wettability between CsPbBr3 perovskite quantum dots (PQDs) and OSCs, fabrication of solution‐processed PQD/OSC PHJs are reported. The phototransistors based on bilayer PQD/PDVT‐10 PHJs show responsivity up to 1.64 × 104 A W−1, specific detectivity of 3.17 × 1012 Jones, and photosensitivity of 5.33 × 106 when illuminated by 450 nm light. Such high photodetection performance is attributed to efficient charge dissociation and transport, as well as the photogating effect in the PHJs. Furthermore, the tri‐layer PDVT‐10/PQD/Y6 PHJs are used to construct photodiodes working in self‐powered mode, which exhibit broad range photoresponse from ultraviolet to near‐infrared, with responsivity approaching 10−1 A W−1 and detectivity over 106 Jones. These results present a convenient and scalable production processes for solution‐processed PHJs and show their great potential for optoelectronic applications. The orthogonal solubility and good wettability between CsPbBr3 perovskite quantum dots (PQDs) and organic semiconductors (OSCs) enable convenient and scalable fabrication of solution‐processed PQD/OSC planar heterojunctions (PHJs) with different configurations, which offer multiple choices to fabricate efficient optoelectronic devices such as phototransistors and photodiodes. The charge transport and dissociation physics at such PHJ interfaces are also investigated and clarified.