Determination of Carrier Lifetimes in Organic-Inorganic Hybrid Solar Cells Based on Sb₂S₃ by Using the Time-Resolved Photocurrent

This paper presents organic-inorganic hybrid solar cells (SCs) based on ZnO/Sb₂S₃/P₃HT heterojunctions. The ZnO and the Sb₂S₃ layers were grown using atomic layer deposition (ALD). Although four cells were fabricated on one substrate by using the same process, their open-circuit voltages (V_OC) and short-circuit current densities (J_SC) were different. The SC with a high V_OC has a low J_SC. The causes of the changes in the V_OC and the JSC were investigated by using photoluminescence (PL) spectroscopy and optically-biased time-resolved photocurrent (TRPC) measurements. The PL results at 300 K showed that the emission positions of the Sb₂S₃ layers in all cells were similar at approximately 1.71 eV. The carrier lifetime of the SCs was calculated from the TRPC results. The lifetime of cell 4 with the highest J_SC decreased drastically with increasing intensity of the continuous-wave optical bias beam. Therefore, the defect states in the ZnO layer contribute to the J_SC, but degrade the V_OC.