Perovskite-CIGS tandem solar cell design set to achieve 29.7% efficiency

Researchers from India's Chitkara University have developed and simulated a two-terminal, stacked tandem solar cell using a top cell made of perovskite with an energy bandgap of 1.68 eV, and a bottom cell based on copper indium gallium selenide (CIGS), with a bandgap of 1.1 eV. Using numerical simulations, the team predicted that the tandem solar cell could achieve an efficiency of 29.72%, an open-circuit voltage of 1.92 V, a short-circuit current of 20.04 mA/cm2, and a fill factor of 77%.

The perovskite layer acts as an absorber for high-energy photons, while the CIGS layer absorbs low-energy photons. Both cells are connected through an intermediate layer of indium tin oxide to match the current for the tandem configuration. The researchers tested different CIGS absorber layer thicknesses from 0.5 μm to 5 μm and found that the current density increased up to 2.3 μm thick absorber layer. They also found that there is a saturation of current density for thickness beyond 2.3 μm.

The researchers used SCAPS-1D solar cell capacitance software to simulate the device’s behavior and performance. The device's optimized absorber thickness was determined to be 2.3 μm, which was found to be efficient in increasing current density due to photon absorption. The study could contribute to the development of more efficient solar cells.