Janus CsPbBr3–AgBiS2 Heteronanocrystals for High-Efficiency Photodetectors

Heteronanocrystals (HNCs) composed of colloidal lead halide perovskites and chalcogenides always offer unique photoelectric properties. Nevertheless, synthesizing perovskite-chalcogenide HNCs has been a tough challenge due to their completely different growth dynamics. Here, we present an effective strategy to synthesize Janus CsPbBr₃-AgBiS₂ HNCs by in situ growth of CsPbBr₃ NCs on prepared AgBiS₂ quantum dot (QDs). The as-synthesized HNCs show a large range of absorption characteristics from visible to near-infrared (NIR) wavebands. Femtosecond transient absorption (TA) spectroscopy reveals the transfer of both electron and hole from CsPbBr₃ to AgBiS₂. The enhanced absorption range and exciton dissociation in 150 °C HNCs leads to photoconductors with drastically improved responsivity (R of 183.8 A W^-1) and specific detectivity (D* of 5.0 × 10¹⁴ Jones). This work not only provides a reliable method for combining ionic CsPbBr₃ and covalent AgBiS₂ but also has great potential for future practical applications, such as an NC (QD) solar cell.