Solution-processed solar cells based on inorganic bulk heterojunctions with evident hole contribution to photocurrent generation

Abstract

To develop solution-processed and novel device structures is of great importance for achieving advanced and low-cost solar cells. In this paper, we report the solution-processed solar cells based on inorganic bulk heterojunctions (BHJs) featuring a bulk crystalline Sb₂S₃ absorbing layer interdigitated with a TiO₂ nanoarray as an electron transporter. A solution-processed amorphous-to-crystalline transformation strategy is used for the preparation of Sb₂S₃/TiO₂-BHJs. Steady-state and dynamic results demonstrate that the crystalline structure in the Sb₂S₃ absorbing layer is crucial for efficient devices, and a better Sb₂S₃ crystallization favors a higher device performance by increasing the charge collection efficiency for a higher short-circuit current, due to reduced interfacial and bulk charge recombinations, and enhancing the open-circuit voltage and fill factor with the reduced defect states in the Sb₂S₃ layer as well. Moreover, an evident contribution to photocurrent generation from the photogenerated holes in the Sb₂S₃ layer is revealed by experimental and simulated dynamic data. These results imply a kind of potential non-excitonic BHJ for energy conversion.