Energy Migration in Organic Solar Concentrators with a Molecularly Insulated Perylene Diimide

Maintaining high incident light absorption while minimizing luminescence reabsorption is a key challenge for organic luminescent solar concentrators (LSCs). Energy migration and trapping using light-harvesting donors and a low-energy highly emitting acceptor is one strategy to reduce the reabsorption issue. However, concentration quenching and the potential formation of quenching aggregates is a limiting factor in realizing efficient devices. We describe the synthesis of a novel molecularly insulated perylene diimide that can resist luminescence quenching at concentrations in excess of 50 mM. Photophysical measurements show the insulated perylene diimide has an excitation energy migration diffusion length of 230 ± 10 Å at 60 mM in poly(methyl methacrylate). LSC devices using a mixture of the insulated perylene diimide light absorber and perylene red (LR305) as the low-energy trap emitter exhibit reduced reabsorption and a better current output than LR305 only devices. The results demonstrate that appropriately designed organic molecule dyes can potentially meet the stringent requirements required for efficient LSCs.