High Open‐Circuit Voltage in Full‐Inorganic Sb2S3 Solar Cell via Modified Zn‐Doped TiO2 Electron Transport Layer

Antimony sulfide (Sb 2 S 3 ) is emerging as a popular photovoltaic candidate for thin‐film solar cells due to its large absorption coefficient, suitable bandgap, nontoxic, and earth‐abundant nature. The performance of thermally evaporated Sb 2 S 3 devices is severely restricted by interfacial recombination leading to high open‐circuit voltage ( V OC ) losses. CdS as electron transport layer (ETL) has overcome this problem, but triggered lower J SC issues due to parasitic absorption loss conceding to its smaller bandgap. Herein, a spray pyrolysis method is adopted for the deposition of a uniform and compact Zn‐doped TiO 2 film with tuned energy levels to facilitate charge extraction and transport. The solar cell fabricated with a modified TiO 2 ETL holds superior interface quality, high build‐in potential, and suppressed recombination losses, therefore pronouncedly improves the V OC . As a result, the efficiency of the device is boosted from 4.41% to 5.16%, a record V OC of 702 mV for Cd‐free full‐inorganic Sb 2 S 3 solar cell is achieved. These findings are expected to be implemented in other Sb‐chalcogenide solar cells to further enhance the device performance.