Enhanced optoelectronic and semiconductor properties of electrodeposited hybrid films: Experimental and DFT-AIM investigation

초록

In this study, 2,2′-bithiophene-copper oxide (PBTh-CuO) hybrid films, containing 5 and 10 wt% CuO, were synthesized on FTO substrates via in situ electrochemical oxidative polymerization of 2,2′-bithiophene in CH3CN containing 0.1 M LiClO4. The resulting films were characterized using cyclic voltammetry, FTIR, UV-Vis spectroscopy, SEM, EDX, AFM, XRD, photoelectrochemical measurements, and Mott-Schottky analysis. In addition, density functional theory (DFT), COSMO and atoms in molecules (AIM) calculations were used to investigate the interfacial electronic properties of the hybrid materials. The incorporation of CuO induced significant structural, optical and electronic modifications compared with pristine PBTh. Increasing the CuO content from 0 to 10 wt% reduced the optical band gap from 1.88 to 1.81 eV, while the acceptor density increased from 2.12 × 1019 to 9.03 × 1019 and 3.4 × 1020 cm−3 for PBTh-CuO (5%) and PBTh-CuO (10%), respectively. AFM analysis revealed a substantial increase in surface roughness, from 10.9 nm for PBTh to 75.7 nm for the CuO-containing films. Theoretical calculations further corroborated the experimental findings, showing a progressive decrease in the HOMO-LUMO gap from 2.45 eV for PBTh to 1.45 eV for PBTh-CuO (5%) and 0.63 eV for PBTh-CuO (10%), accompanied by enhanced dipole moment and interfacial charge polarization. AIM analysis indicated that interface stabilization is dominated by strong S·O polar interactions, supplemented by weaker Cu-centered contacts. Consequently, the incorporation of CuO significantly enhances the optoelectronic and interfacial properties of PBTh, highlighting the potential of PBTh-CuO hybrid films for photoelectrochemical and optoelectronic applications.

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