Electrical performance of the perovskite solar cells with 3D patterned layers

A 3D-patterned back-electrode architecture is developed to enhance the optoelectronic performance and mechanical durability of flexible perovskite solar cells. Truncated pyramidal microstructures are fabricated on flexible substrates via a previously developed single-step greyscale lithography process, followed by vacuum thermal evaporation of an aluminum electrode and conformal spray-coating of the subsequent layers. This approach addresses the inherent performance-durability trade-off in flexible electronics - by using structures with a truncated geometry, localized stress concentrations are mitigated while back-reflection into the absorber layer is maximized. The optimized 3D architecture achieves a power conversion efficiency of 20.3% and a fill factor of 70%, significantly exceeding the values of planar devices - 16.6% and 61%, respectively. These improvements are primarily driven by enhanced charge collection kinetics and reduced interfacial charge-transfer resistance, complemented by optical back-reflection benefits. Furthermore, the patterned electrode demonstrates an 85-fold improvement in electromechanical stability, maintaining a sheet resistance of 52 Ω/sq. after 10,000 bending cycles, whereas the planar electrode exhibits failure exceeding 4.5 kΩ/sq. The synergistic integration of greyscale lithography with truncated geometries provides a scalable microfabrication route to resolve the conflict between optical trapping and mechanical resilience, positioning 3D texturing as a critical advancement for next-generation flexible photovoltaics.