Stability enhancement of polymer solar cells in trilayer configuration

Inverted organic solar cells by bulk-heterojunctions were fabricated using TiO₂ and ZnO as electron extraction layers. Electrospray deposition was applied to fabricate trilayer structures with thin donor and acceptor layers sandwiching bulk-heterojunction layers. Comparing to single layer devices, trilayer devices show significantly enhanced stability in device performances under continuous illumination in air. Conventional structure devices with Al as electron extraction layer were also compared showing how the improvement achieved with the inverted architecture is surprisingly higher. Our results, on a basis of 4 h of continuous operations, show how combining inverted device architecture with trilayer configuration is a viable approach in achieving highly stable organic solar cells with 70% retainment of the initial PCE to be compared to the 13% in the case of direct trilayer BHJ. - Highlights: • Significant enhancement of inverted trilayer bulk heterojunction solar cells (SCs) • 70% of its initial PCE value retainment after 4 h operation in air • Huge improvement of retainment with respect to direct device architecture (3%) • SC lifetime related to electrode/layer interface rather than electrode degradation. • Interface quality is improved by the specific electro-spray method.