Lifetime Study of Organic Solar Cells with O-IDTBR as Non-Fullerene Acceptor

Organic solar cells (OSCs) have increased their power conversion efficiency above 18% thanks to the use of non-fullerene acceptors in binary or ternary blends or in tandem configurations. In this article, a study on the lifetime of P3HT:O-IDTBR bulk heterojunction OSCs on ITO-free flexible substrates is presented. A direct comparison of glass–glass and plastic–plastic encapsulation performance, with a special focus on its effect on the lifetime of the devices after degradation procedures, has been carried out complying with the ISOS protocols for organic photovoltaic devices. The manufactured OSCs with 1 cm² active layer have power conversion efficiencies ranging from 1.9 to 3.4% depending on the encapsulant material, encapsulation process, and substrate. An exponential degradation rate has been found, with a similar functional behavior for glass and plastic differing in the degradation constants, which ranges from k = 0.01 to 0.002 h⁻¹. Only in one case, the ISOS-T3 essay for plastic encapsulation, a double exponential process, was observed with degradation rates of k₁ = 0.03 h⁻¹ and a second slower process with k₂ = 0.001 h⁻¹. The longest achieved T₈₀ lifetime is 86 h for glass-encapsulated devices under an accelerated ISOS-T3 protocol.