Trilaminar ZnO/ZnS/Sb2S3 nanotube arrays for efficient inorganic–organic hybrid solar cells

Abstract

Efficient hybrid solid-state solar cells based on novel trilaminar ZnO/ZnS/Sb₂S₃ nanotube arrays (NTs) and poly(3-hexylthiophene) (P3HT) are fabricated by using a buffer layer using ZnS and surface modification using a sensitizer layer (Sb₂S₃). Vertically aligned trilaminar ZnO/ZnS/Sb₂S₃ nanotube arrays (NTs) were directly grown on an indium-doped tin oxide (ITO) substrate via a low-cost hydrothermal chemical conversion method based on ion exchange, which is easy to be manipulated and can form uniform structures without destroying the original morphology. The ZnO/ZnS/Sb₂S₃/P3HT hybrid solar cell exhibited an improved short-circuit current density (J_sc) of 5.57 mA cm⁻², open-circuit voltage (V_oc) of 440 mV, giving rise to a power conversion efficiency of 1.32%. The trilaminar architecture is able to suppress carrier recombination and increase electron collection efficiency via (i) increasing photon absorption through a sensitizer layer (Sb₂S₃), (ii) forming a buffer layer (ZnS) on the surface of ZnO NTs in the chemical conversion process and (iii) a better energy level alignment in the ZnO/ZnS/Sb₂S₃/P3HT.