Oxide vacancy passivation through interface engineering of Tetraphenylethylene-Based Small-Molecule with sulfonate functional group for efficient organic photodetector

In this study, an alcohol-soluble tetraphenylethylene (TPE) unit-based luminogen with sulfonate chains is developed as a passivation layer for the oxygen vacancies of zinc oxide (ZnO) to obtain efficient organic photodetectors (OPDs). Given that the TPE-4 is designed to have four sulfonate chains, it can effectively fill the oxygen vacancy in ZnO, as confirmed by the results of X-ray photoelectron spectroscopy. The OPD device with the combination of ZnO and TPE-4 buffer layer exhibited decreased dark current and increased photocurrent owing to the prevention of trap-assisted recombination and shunt leakage caused by oxygen vacancies, as proved by electrical analysis. Moreover, the TPE-4 buffer layer exhibited excellent noise attenuation, leading to a signal-to-noise ratio of 50.35 dB and high device speeds of 0.77 μs and 137 kHz. The proposed TPE-based luminogen, designed to highlight the advantages of the widely used metal oxide layer while compensating for its limitations, is an effective strategy for realizing excellent photodetectors through chemical bonding.