Enhancement of Electron Mobility and Optoelectrical Performance Behaviour of Polycarbazoles Featured with Zinc Oxide Nanoparticles

Abstract

The PCDTBT ((Poly[N-9′-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)) is a familiar conjugated polymer utilized for optoelectronic and solar cell applications due to its significant functional characteristics, including wide absorption, improved open-circuit voltage, and suitability for solution processing. However, it found reduced variation in electron mobility, which affected the short-circuit current density and, consequently, the power conversion efficiency properties. This research overcomes the consequence and enriches the overall optoelectronic behaviour of PCDTBT-based organic photovoltaic (OPV) with an adaptation of zinc oxide (ZnO) electron transport layer (ETL) as 0, 10, 20, 30, and 40 nm thicknesses via radio frequency (RF) magnetron spattering technique and influences of ZnO ETL layer thickness on optical, electron mobility, charge transport, X-ray diffraction and PL (Photoluminescence) efficiency of PCDTBT is investigated. The optimized OPV structure features 40 nm ZnO nanoparticles incorporated into the PCDTBT active layer. The optimized structure achieves an open-circuit voltage (VOC) of 0.91 V, a short-circuit current density (JSC) of 15.09 mA/cm², and a power conversion efficiency (PCE) of 8.5%. The photoluminescence efficiency was limited by 35%, and the charge mobility was significantly enhanced with electron and hole mobility of 1.2 × 10^–3 and 1.9 × 10^–4 cm²/V s. The crystallinity of PCDTBT was improved due to the wurtzite structure of ZnO achieving a maximum crystalline size of 26 nm. The results highlight the crucial role of optimizing the ZnO layer in achieving high-performance PCDTBT: ZnO OPV devices.