Correlation Between Surface Functionalization and Optoelectronic Properties in Quantum Dot Phototransistors

Abstract

Quantum dot (QD)-based optoelectronics have attracted significant interest for extensive applications due to their unique photo-functionalities such as excellent optical absorption coefficient, size-dependent bandgap tunability, and facile solution processability. However, the charge transfer correlation between surface functionalization and optoelectronic properties is still not clear. Here, we report highly photosensitive CdSe QDs/solution-processed amorphous oxide semiconductor hybrid phototransistors with highly efficient photo-induced charge carrier transport using molecular metal chalcogenide (MCC) ligands surface functionalization. Furthermore, we comprehensively investigated the photo-induced electron transfer characteristics with respect to various MCC ligands such as Sn<inline-formula> <tex-math notation= LaTeX >$_{{2}}\\,\\,\\text{S}_{{6}}^{{4-}}$ </tex-math></inline-formula>, Sn₂ Se<inline-formula> <tex-math notation= LaTeX >$_{{6}}^{{4-}}$ </tex-math></inline-formula>, and In₂ Se<inline-formula> <tex-math notation= LaTeX >$_{{4}}^{{2-}}$ </tex-math></inline-formula>. In particular, the interplay among photosensitive chelating MCC ligands of the QDs and trap-free optoelectronic performance of phototransistors was investigated. Compared to <inline-formula> <tex-math notation= LaTeX >${a}$ </tex-math></inline-formula>-IGZO thin-film transistors and oleic acid-based CdSe QDs/<inline-formula> <tex-math notation= LaTeX >${a}$ </tex-math></inline-formula>-IGZO phototransistors, Sn<inline-formula> <tex-math notation= LaTeX >$_{{2}}\\,\\,\\text{S}_{ {6}}^{ {4-}}$ </tex-math></inline-formula>, Sn₂ Se<inline-formula> <tex-math notation= LaTeX >$_{ {6}}^{ {4-}}$ </tex-math></inline-formula>, and In₂ Se<inline-formula> <tex-math notation= LaTeX >$_{ {4}}^{ {2-}}$ </tex-math></inline-formula>-based CdSe QD/<inline-formula> <tex-math notation= LaTeX >${a}$ </tex-math></inline-formula>-IGZO phototransistors exhibited ultrahigh photosensitivity of <inline-formula> <tex-math notation= LaTeX >$8.3\\times 10 ^{ {3}}$ </tex-math></inline-formula> AW⁻¹, <inline-formula> <tex-math notation= LaTeX >$3.1\\times 10 ^{ {2}}$ </tex-math></inline-formula> AW⁻¹, and <inline-formula> <tex-math notation= LaTeX >$1.3\\times 10 ^{ {4}}$ </tex-math></inline-formula> AW⁻¹, respectively, in a broad range of incident light power (0.34 mW cm⁻² −11.8 mW cm⁻²).