Efficient Triplet Harvesting in an Air-stable Diketopyrrolopyrrole Singlet Fission Solar Cell

Diketopyrrolopyrrole (DPP) is an air-stable molecule which has recently been shown through spectroscopic investigation to host excitonic singlet fission (SF). Here we synthesize DPP-based solar cells using dicyano naphthalene diimide (dCN NDI) acceptor molecules and quantify SF generated carrier extraction efficiency. The characteristic dependence of the photocurrent as a function of magnetic field, which is the unambiguous signature of SF, is observed. Furthermore, we show that DPP-based photovoltaic devices are remarkably air-stable, unencapsulated devices do not exhibit a degradation of electrical or photovoltaic properties as a result of aging. Therefore, DPP is promising material for organic SF photovoltaic devices