Antimony selenide solar cell with 6.4% efficiency

Scientists from the University of Toledo in the United States have developed a 6.43%-efficient solar cell based on antimony selenide (Sb₂Se₃), which is a little studied absorber material that nonetheless has a near-direct bandgap of ~1.2 eV and excellent optoelectronic properties.

The cell, which they described as a low-cost and environmentally friendly device, was fabricated by depositing the Sb₂Se₃ films on soda-lime glass substrates coated with molybdenum (Mo) using closed space sublimation (CSS), which is a physical vapor deposition process commonly used in the production of thin-films and cadmium telluride (CdTe) panels.

A bulk Sb₂Se₃ absorber layer was deposited using the source plate. “The obtained absorber layers were then selenized at temperatures from 350 to 450 degrees Celsius in argon at a base pressure of 10 Torr with 100 mg selenium for 30 minutes to promote the recrystallization of Sb₂Se₃,” the academics explained.

After this production step was concluded, the group deposited a 55 nano-meter thick cadmium sulfide (CdS) buffer layer onto the absorber using chemical bath deposition. They then deposited a front contact layer comprising a 50 nm high-resistive intrinsic zinc oxide (i-ZnO) layer and a 250 nm aluminum-doped zinc oxide (ZnO:Al) via radio frequency (RF) sputtering. All these layers were scribed together to form a solar cell with an active area of 0.2 cm².

“The results indicate that a proper selenization temperature is critical to achieving Sb₂Se₃ films with large grains, uniform morphology, high crystallinity, desired crystal orientations, and increased carrier density,” the researchers stated.

The device is presented in the paper Influence of Post-selenization Temperature on the Performance of Substrate-Type Sb₂Se₃ Solar Cells, published in ACS Publications.