Janus CsPbBr₃–AgBiS₂ Heteronanocrystalsfor 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 (<i>R</i> of 183.8 A W^–1) and specific detectivity (<i>D</i>* 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.