Lead-free Cs2BiAgI6 has garnered a lot of
research interest recently due to its suitability as a potential absorber
layer in the solar cell (SC) architecture owing to its low cost, good
stability, and high efficiency. The main highlight of this research
work includes the photovoltaic (PV) performance enhancement of Cs2BiAgI6 double perovskite solar cells (PSCs) by
optimizing the optoelectronic parameters of the absorber, electron
transport layer (ETL), hole transport layer (HTL), and various interface
layers. Solar Cell Capacitance Simulator One dimension (SCAPS-1D)
numerical simulation was used to optimize the performance of Cs2BiAgI6 absorber-based SCs consisting of copper
barium thiostannate (CBTS) as the HTL and TiO2, PCBM, ZnO,
IGZO, SnO2, and WS2 as ETLs. The role of the
non-lead cesium-based halide perovskite absorber layer in the improvement
of the SC performance was systematically investigated through a variation
in the thickness, doping density, and defect density of the absorber
layer, ETL, and HTL. The performance of the investigated device architectures
is largely dependent on the thickness of the absorber layer, acceptor
density, defect density, and the combination of different ETLs and
HTLs. We found that TiO2, PCBM, ZnO, IGZO, SnO2, and WS2 ETL-based optimized devices recorded a power
conversion efficiency (PCE) of 23.14, 23.71, 23.69, 22.97, 23.61,
and 21.72%, respectively. Furthermore, the effect of series and shunt
resistances, temperature, capacitance, and Mott–Schottky for
the six optimized devices was estimated along with the computation
of the corresponding generation and recombination rates, current density–voltage
(J–V), and quantum efficiency
(QE) characteristics. The PV parameters obtained from this comprehensive
analysis are finally compared with the earlier published theoretical
and experimental reports on Cs2BiAgI6 absorber-based
SCs.