Enhanced performance of ZnO microwire/PEDOT:PSS heterojunction ultraviolet photodetectors via carbon nanohorns and DMSO treatment

Abstract

Conducting polymers with stability, flexibility and transparency are highly desired as the crucial component of multifunctional wearable electronic devices due to the growing requirements but suffer from poor electrical characteristics. In this work, carbon nanohorns (CNHs) and dimethyl sulfoxide (DMSO) were employed to modulate the electrical performances of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) samples. Combining a Ga-doped ZnO microwire (ZnO:Ga MW), the treated PEDOT:PSS sample was used to fabricate an inorganic–organic heterojunction photodetector. The device exhibited excellent photoresponse properties, containing a rectification ratio of 10⁵, a responsivity of 0.273 A W⁻¹, a specific detectivity of 1.17 × 10¹² Jones and an external quantum efficiency (EQE) of about 91.5% under 370 nm light illumination in a self-driving operation manner. Compared with the detector that uses untreated PEDOT:PSS, the performance features of the rectification ratio, photoresponsivity, specific detectivity and EQE have been distinctly increased over 9.0, 10.9, 9.1 and 10.9 times, respectively. In particular, the response times were greatly reduced from 1.53/16.9 ms to 152 μs/13.5 ms. The enhanced photoresponse characteristics were ascribed to the increased photoelectrical properties of the treated PEDOT:PSS via the CNHs&DMSO co-additive. The electrical conductivity of the DMSO treated PEDOT:PSS was remarkably increased, thus leading to an enhanced rectification ratio of the fabricated n-ZnO:Ga MW/p-PEDOT:PSS heterojunction while the improved photoresponse performances mainly originated from the incorporated CNHs, supplying a high-efficiency transport channel for the photogenerated electron–holes. This work can provide a potential candidate for developing high-performance flexible optoelectronic devices.