Enhanced optoelectronic and mechanical properties of P3HT/ZnO nanowire hybrid films for bulk heterojunction solar cells

Poly(3-hexylthiophene) (P3HT) is a widely studied material characterized by excellent carrier transport properties, enhanced light absorption, and flexibility. However, low electrical conductivity compared to inorganic semiconductors, interface compatibility issues, and reduced power conversion efficiency are the primary challenges for P3HT. This study investigates the enrichment of flexibility and optoelectronic properties of P3HT by incorporating zinc oxide (ZnO) nanowires specifically targeted for bulk heterojunction solar cell applications. The study explores novel ZnO nanowires with varying P3HT: ZnO ratios (1:1, 1:2, 1:3, and 1:4) fabricated via the spin-coating technique at 1500 rpm for 30 s for the deposition of high-quality thin films (ITO/P3HT:ZnO/Ag), associated with the post-annealing process at 120ºC for 30 min. Key performance metrics include X-ray diffraction, absorption spectra, I–V characteristics, mobility, power conversion efficiency, external quantum efficiency, and flexibility. The incorporation of ZnO nanowires significantly enhanced the optoelectronic properties of P3HT thin films. Optimal performance in heterojunction solar cells was achieved with a 1:3 P3HT:ZnO composition, with a crystalline size of 45 nm. The film’s absorption was increased to 34%. This composition achieved a short-circuit current of 3.4 mA and an open-circuit voltage of 1.2 V. The mobility was increased to 5.5 × 10^–4 cm²/V.s with power conversion efficiency of 4.35% and external quantum efficiency of 51%. The film’s flexibility decreased with the addition of ZnO, while its durability improved. Furthermore, this ITO/P3HT:ZnO/Ag thin-film solar cell is novel for its optimal open-circuit voltage and enhanced power conversion efficiency.