A theoretical study on Sb₂S₃ solar cells: The path to overcome the efficiency barrier of 8%

Sb₂S₃ semiconductor is among the absorber materials that have currently received an increased attention from scientific community since it presents adequate physical properties for solar cell fabrication. In addition, it is also based on abundant and relatively low-toxic elements. Nevertheless, so far, Sb₂S₃ solar cells in planar configuration are limited to efficiency values lower than 8%, being mechanisms behind such low performances still unknown. In this work we perform theoretical calculations to study the impact of recombination mechanisms at both Sb₂S₃ bulk material and Sb₂S₃/CdS interface on solar cells, in order to explain low efficiencies reported for this technology, for the first time. The comparison of model outcomes to the experimental data reported in the literature demonstrates good correspondence. It is found that current Sb₂S₃ solar cells are dominated by a combination of factors such as non-ideal series and shunt resistances, Sb₂S₃ non-radiative recombination and Sb₂S₃/CdS interface recombination. By improving Sb₂S₃/CdS interface and Sb₂S₃ bulk material quality, a solar cell efficiency of 11.8% could be achieved, which is limited by the effect of series and shunt resistances. Therefore, the same attention should be paid to both defects and resistances to promote device efficiency over 12%, achieving a new record value of 18.4%. Conditions under which each loss mechanism is dominant are presented and discussed. Finally, it is demonstrated that under optimized conditions and with the use of an antireflection coating layer, an efficiency about 20% is expected.