Correlation Between Surface Functionalization 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-2 S-6(4-), Sn-2 S-6(4-), and In-2, 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 ODs/a-IGZO phototransistors, Sn-2 S-6(4-), Sn-2 Se-6(4-), and In-2 Se-4(2-) -based CdSe QD/a-IGZO phototransistors exhibited ultrahigh photosensitivity of 8.3 x 10(3) AW(-1), 3.1 x 10(2) AW(-3), and 1.3 x 10(4) AW(-1), respectively, in a broad range of incident light power (0.34 mW cm(-2) -11.8 mW cm(-2)).