Production of Se-nanorods-rGO nanocomposite for use as a counter electrode in dye-sensitized solar cells

Abstract

A Se nanorods-modified reduced graphene oxide (rGO) nanocomposite was synthesized via a reflux method at 150 °C and evaluated as a platinum-free counter electrode (CE) for dye-sensitized solar cells (DSSCs) Morphological analyses using FESEM and TEM showed that selenium nanorods are densely packed, measuring approximately 1 µm in length and 120 nm in diameter. These nanorods are uniformly distributed on the surface of reduced graphene oxide (rGO), creating a strong interfacial contact. XRD and HR-TEM confirmed the crystalline trigonal phase of selenium and the successful reduction of GO. Electrochemical impedance spectroscopy (EIS) shows a decrease in charge transfer resistance for Se nanorods-rGO (Rct = 23.4 Ω) compared to pristine rGO (Rct = 27.58 Ω), which suggests that the former has a greater tri-iodide reduction electrocatalyst activity. From the J–V characteristics measured under AM 1.5 illumination, the power conversion efficiencies (PCE) were obtained as 3.14% and 3.28% for TcSeCl4 concentrations of 0.2 g and 0.1 g, respectively. The corresponding short circuit current densities (Jsc) were 9.52, 10.68 mA·cm⁻², open-circuit voltages (Voc) were 0.576, 0.582 V, and fill factors (FF) values were 0.572, 0.527. These results substantially enhance pristine rGO (η = 1.72%, FF = 0.42). The Se nanorods-rGO composite also showed good stability and performance retention under testing conditions. These findings position Se nanorods-rGO as a promising, cost-effective material for high-performance, stable counter electrodes in DSSCs.

Graphical Abstract

The results are promising as the proposed Se-nanorods-rGO nanocomposite reveals the highest efficiency (3.24 %) compared to the pristine graphene oxide (GO).