Ultrahigh Gain Polymer Photodetectors with Spectral Response from UV to Near‐Infrared Using ZnO Nanoparticles as Anode Interfacial Layer

Abstract

Significant increase of photocurrent upon UV light exposure is demonstrated in a narrow‐bandgap polymer‐based photodetector using ZnO nanoparticles as anode interfacial layer. The phenomenon is attributed to the UV light illumination induced oxygen molecules desorption from surface of ZnO nanoparticles, which reduces the electron injection barrier at the anode interface. Ultrahigh external quantum efficiency of 140 000% and extremely low gain threshold voltage of 1.5 mV are achieved in this device with 30 s UV light irradiation. The gain mechanism is explained by the fast transit and replenishment of photogenerated electrons within their lifetime, which is prolonged by the electron‐only device structure, and the experiment results fit well with the proposed photoconductive model.

Recent Progress on Photomultiplication Type Organic Photodetectors

“…Ma et al. demonstrated the OPDs with significant photocurrent multiplication by directly using ZnO NPs as interfacial layer upon UV light exposure . Figure a exhibits the device structure of OPDs.…”

“…a) Schematic diagram of device structure; and schematic of UV light induced oxygen desorption from ZnO NPs surface and the concomitant change in surface energy level structure and free electron density in the cases of b) pristine, c) under UV light illumination, and (d) after UV light treatment.All panels reproduced with permission . Copyright 2016, Wiley‐VCH.…”

“…Working mechanism of the photodetector in dark and under illumination, with a) and b) before and c) and d) after UV light treatment. All panels reproduced with permission . Copyright 2016, Wiley‐VCH.…”

Low‐Bandgap Terpolymers for High‐Gain Photodiodes with High Detectivity and Responsivity from 300 nm to 1600 nm

“…used UV‐irradiated ZnO nanoparticles as interlayer in PPDs and achieved high photocurrent gain by enhancing the electron tunneling from the electrode owing to the effect of interface charge trapping. The device exhibited the EQE of as high as 140000% …”

High‐Performance Polymer Photodetector Using the Non‐Thermal‐and‐Non‐Ultraviolet–Ozone‐Treated SnO2 Interfacial Layer

“…The trapped photogenerated electron accumulation at the interface results in a band bending. In addition, the conductivity of SnO 2 increases and the electron injection barrier from ITO to SnO 2 decreases when the trap states of the SnO 2 nanoparticle film are occupied by the charge carriers . Therefore, a large number of electrons can tunnel into the device, leading to a significantly large photocurrent.…”