Influence of complexing agents-aided CuInSe2 thin films by single-step electrochemical deposition and photoelectrochemical studies

Abstract

CuInSe2 thin films were deposited on ITO glass substrate by one-step electrochemical deposition (ECD) method without and with complexing agents like tetramethyl ammonium hydroxide (TMAH) and triethanolamine (TEA) at different temperatures. X-ray diffraction (XRD) studies confirm the as-deposited CuInSe2 thin films at 85 °C without and with complexing agents belong to the tetragonal crystal structure with the dominant peak representing the (112) plane. The single crystallized CuInSe2 thin films show Raman spectra with a dominant A1 mode at 174 cm−1. Raman spectra analysis conform that doesn’t peak present secondary phases like Cu2S and In2S3. AFM images of the as-deposited thin films show adherent, compact, and crack-free surface. The (αhν)2 fall is sharper in CuInSe2 thin films with TEA complex than the TMAH complex due to better crystallinity. From the electrochemical impedance spectroscopy (EIS) study, we found that CuInSe2 thin film with TEA complex acquires a very slighter charge transfer resistance (Rct) of 32 Ω when compared with CuInSe2 thin film samples deposited with and without TMAH. Also, photoelectrochemical investigation signifies that CuInSe2 thin films deposited with TEA complex exhibit engendering better photocurrent response and more rapid relocation of photo-induced charge carriers in contrast to the other thin films fabricated with TMAH. We observed from cyclic voltammetry (CV) studies that redox reaction of iodide/triiodide (I−/I−3) optimized using CuInSe2 thin film with TEA complex delivers superior electrocatalytic performance than the films with TMAH.