Optical design and optimization for back-contact perovskite solar cells

Interdigitated back-contact (IBC) structure has been successful explored for optimal light-harvesting in the silicon solar cells (SCs), but less used in perovskite solar cells (PSCs). To unlock the full potential of IBC PSCs, we investigate numerically the photo-electrical performance of this type of IBC PSCs, designing the light-trapping structures and screening the functional materials. Taking the experimental quasi-interdigitated back-contact (QIBC) structure as the original model, the optical absorption of PSCs can be boosted by befitting anti-reflective coating thickness and rear substrate materials. And then the QIBC PSC yields the maximal photocurrent density of 24.03 mA/cm2, 4.19 mA/cm2 higher than that of the conventional sandwich PSC. The light-trapping effect of QIBC architecture is discussed by addressing the absorption spectra and the cross-sectional electric field distributions of perovskite layer. Besides, better optical properties can be well maintained in a large range of film thickness and band gap of perovskite, as well as incident angles, compared with that of sandwich PSC. More importantly, an approximate electrical simulation is implemented, revealing the relationship between the internal quantum efficiency, the carrier diffusion length of perovskite and the electrode finger distance. Therefore, the simulation results are expected to provide the theoretical guidance for developing high efficiency IBC PSCs.