All-solution-processed UV-IR broadband trilayer photodetectors with CsPbBr₃ colloidal nanocrystals as carriers-extracting layer

Colloidal quantum dots (CQDs) are very promising nanomaterials for optoelectronics due to their tunable bandgap and quantum confinement effect. All-inorganic CsPbX₃ (X = Br, Cl and I) perovskite nanocrystals (NCs) have attracted enormous interests owing to their promising and exciting applications in photovoltaic devices. In this paper, all-solution-processed UV-IR broadband trilayer photodetectors ITO/ZnO/PbS/CsPbBr₃/Au and ITO/ZnO/CsPbBr₃/PbS/Au with high performance were presented. The role of CsPbBr₃ QDs layer as the carriers-extracting layer in the trilayer devices was discussed. As compared with bilayer device ITO/ZnO/PbS/Au, both the dark currents and photocurrents under illumination from trilayer photodetectors are enhanced, but the trilayer photodetector ITO/ZnO(80 nm)/PbS(150 nm)/CsPbBr₃(50 nm)/Au showed a maximum specific detectivity (D∗) of 8.3 × 10¹² Jones with a responsivity (R) of 35 A W^-1 under 1.6 mW cm^-2 980 nm illumination. However, another trilayer photodetector ITO/ZnO(80 nm)/CsPbBr₃(50 nm)/PbS(150 nm)/Au showed a maximum D∗ of 1.73 × 10¹² Jones with a R of 5.31 A W^-1 under 6.8 mW cm^-2 405 nm illumination. Further, the underlying mechanism for the enhanced performance of trilayer photodetectors was discussed. Thus, this strategy of all-solution-processed heterojunction configuration paves a facile way for broadband photodetectors with high performance.