Investigating the impact of thermal annealing on the photovoltaic performance of chemical bath deposited SnO₂/p-Si heterojunction solar cells

The current work investigates the impact of annealing temperature on the optoelectronic properties of SnO₂ thin films grown by chemical bath deposition (CBD) method. The as-grown SnO₂ films, on p-Si substrate, are annealed at 200 °C and 400 °C for 10 min in Ar ambient for investigating the impact of such annealing on the performance of SnO₂/p-Si heterojunction solar cells. The growth of a uniform SnO₂ film on Si surface has been confirmed from SEM studies and the chemical composition and optical properties of the as-grown and annealed films are investigated in detail by employing XRD and ellipsometric measurements. Absorption coefficient of the samples is observed to vary in the range of 24 × 10⁵ – 60 × 10⁵/m, at its band gap (3.0 eV). The current–voltage characteristics under both dark and illuminated conditions suggest superior voltaic performance of the 200 °C annealed SnO₂ film. The short-circuit current density, open-circuit voltage and fill-factor are obtained to be 0.45 mA/cm², 5.41 mA/cm² and 0.4 V, 0.34 V and 13%, 8% respectively for as-grown and 200 °C annealed samples. The maximum power conservation efficiency (η) of 4.9% is obtained for the 200 °C annealed sample. Thus, the study indicates the potential of CBD-grown SnO₂ film for photovoltaic applications.