Reducing non-radiative voltage losses in organic solar cells using molecular encapsulation

Abstract

Non-radiative voltage loss is one of the significant bottlenecks limiting the performance of organic solar cells (OSCs). This work presents a material design approach for conjugated polymers isolating the polymer chains with molecular encapsulation, enabling better control over the donor-acceptor spacing. Bulk-heterojunction OSCs based on encapsulated polymers as electron donors show a remarkable increase of ∼50 mV in the Voc. Significant improvement in the Voc is attributed to reduced non-radiative voltage losses as evidenced by enhanced electroluminescence as a result of suppressed intermolecular aggregation and an increase in structural disorder. Importantly, molecular encapsulation resulted in notable improvement in the operational stability of OSCs with no burn-in loss in Voc, presenting a promising strategy to simultaneously enhance the performance and operational stability of OSCs.