Doping in TiO2 to improve solar cell efficiency: A Comprehensive Review

To enhance the performance and stability of these solar cells, doping of titanium dioxide (TiO2) with elements such as aluminum (Al), neodymium (Nd), and samarium (Sm) has been explored. This abstract provides a summary of the properties affected by Al, Nd, and Sm doping in TiO2 and their impact on DSSCs and PSCs. Al, Nd, and Sm doping in TiO2 have shown improvements in various properties critical to solar cell performance. The reduction of non-stoichiometric oxygen-induced defects through doping results in the removal of deep electronic traps and sub-bandgap states, leading to an increase in the conduction band. This modification contributes to enhanced charge transport and reduced recombination rates within solar cell devices. Furthermore, the doping process facilitates the passivation of oxygen defects, which plays a crucial role in improving the stability of PSCs. Nd doping has shown promising results in enhancing device stability without compromising short-circuit current. The simple and scalable processing techniques employed for doping TiO2 with these elements make them viable for large-scale production. The achieved efficiencies in DSSCs and PSCs vary depending on the specific calculation methods used, including preconditioning bias, voltage scan speed, and direction. Nevertheless, studies have reported significant efficiency improvements with optimal doping concentrations. For instance, a maximum efficiency of 18.2% was recorded in PSCs with 0.3% Nd doping in TiO2, where maximum values for current density (JSC), open-circuit voltage (VOC), and fill factor (FF) were obtained.