Emerging BaZrS and Ba(Zr,Ti)S Chalcogenide Perovskite Solar Cells: A Numerical Approach Toward Device Engineering and Unlocking Efficiency.

BaZrS chalcogenide perovskites have emerged as a promising absorber due to their exceptional properties. However, there are no experimental reports on the applicability of BaZrS in photovoltaics. Thus, theoretical knowledge of device structure engineering is essential for its successful fabrication. In this regard, we have proposed various BaZrS device configurations by altering 12 electron transport layers (ETLs) in combination with 13 hole transport layers (HTLs) using SCAPS-1D, wherein a total of 782 devices are simulated by tuning the thickness, carrier concentration, and defect density of BaZrS, ETLs, and HTLs. Interestingly, the absorber's thickness optimization enhanced the absorption in the device by 2.31 times, elevating the generation rate of charge carriers, while the increase in its carrier concentration boosted the built-in potential from 0.8 to 1.68 V, reducing the accumulation of charge carriers at the interfaces. Notably, on further optimization of ETL and HTL combinations, the best power conversion efficiency (PCE) of 28.08% is achieved for FTO/ZrS/BaZrS/SnS/Au, occurring due to the suppressed barrier height of 0.1 eV at the ZrS/BaZrS interface and degenerate behavior of SnS, which increased charge carrier transportation and conductivity of the devices. Upon optimizing the work function, an ohmic contact is achieved for Pt, boosting the PCE to 28.17%. Finally, the impact of Ti alloying on BaZrS properties is examined on the champion FTO/ZrS/BaZrS/SnS/Pt device where the maximum PCE of 32.58% is obtained for Ba(Zr,Ti)S at a thickness of 700 nm due to extended absorption in the NIR region. Thus, this work opens doors to researchers for the experimental realization of high PCE in BaZrS devices.