Correlation Between Surface Functionalization and Optoelectronic Properties in Quantum Dot Phototransistors

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 $_{{2}}\,\,\text{S}_{{6}}^{{4-}}$ , Sn2 Se $_{{6}}^{{4-}}$ , and In2 Se $_{{4}}^{{2-}}$ . In particular, the interplay among photosensitive chelating MCC ligands of the QDs and trap-free optoelectronic performance of phototransistors was investigated. Compared to ${a}$ -IGZO thin-film transistors and oleic acid-based CdSe QDs/ ${a}$ -IGZO phototransistors, Sn $_{{2}}\,\,\text{S}_{ {6}}^{ {4-}}$ , Sn2 Se $_{ {6}}^{ {4-}}$ , and In2 Se $_{ {4}}^{ {2-}}$ -based CdSe QD/ ${a}$ -IGZO phototransistors exhibited ultrahigh photosensitivity of $8.3\times 10 ^{ {3}}$ AW−1, $3.1\times 10 ^{ {2}}$ AW−1, and $1.3\times 10 ^{ {4}}$ AW−1, respectively, in a broad range of incident light power (0.34 mW cm−2 −11.8 mW cm−2).