Enhanced light trapping in thin-films perovskite solar cells by photonic crystal structures

To boost light harvesting in perovskite thin-film solar cells, we introduce a dual photonic crystal (PhC) architecture that significantly enhances light trapping and device performance. A one-dimensional photonic crystal (1D-PhC), implemented as a distributed Bragg reflector composed of alternating dielectric layers, functions as a highly reflective and low-loss back mirror. Complementarily, a two-dimensional photonic crystal (2D-PhC) pattern is embedded in a flexible poly-dimethylsiloxane substrate replacing conventional glass, effectively minimizing front-surface reflection. The geometries of both photonic structures are carefully optimized to promote efficient photon diffraction and prolong the optical path within the absorber layer, thereby maximizing light absorption. This hybrid PhC configuration enables superior light trapping and enhances the optical field confinement in the active perovskite layer. In addition, interface engineering is employed to reduce carrier recombination losses, further boosting overall device performance. Numerical simulations, conducted using the rigorous coupled wave analysis method via SYNOPSYS RSoft CAD tools, demonstrate a notable improvement in the short-circuit current density (Jsc), which increases from 21.3 mA/cm2 in the planar structure to 39.6 mA/cm2, an enhancement of 85%. Correspondingly, the power conversion efficiency rises from 15.8% to 26.1%, representing a substantial 65% relative improvement. These results underscore the potential of photonic crystal integration for next-generation high-efficiency perovskite solar cells.