Approaching the ultimate open circuit voltage in thiophene based single junction solar cells by applying diindenoperylene as acceptor

The efficiency of a photovoltaic cell is directly proportional to its open circuit voltage. This in turn is eventually set by the donor‐acceptor energy gap, i.e. the energy of the intermolecular charge‐transfer state in organic solar cells. In this letter we study diindenoperylene (DIP) as a new molecular acceptor. We show that planar heterojunctions of thiophene derivatives and DIP yield extraordinarily high open circuit voltages (Voc) of approximately 1.2 V for poly(3‐hexylthiophene) and almost 1.4 V for heat treated α‐sexithiophene. Those values are close to the maximum Voc attainable for these material systems. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) In this Letter the authors introduce diindenoperylene (DIP) as new molecular acceptor in organic solar cells. They demonstrate that DIP can act both as the electron donor as well as the acceptor depending on its partner material. They also show that DIP yields an extraordinarily high open circuit voltage of almost 1.4 V when employing sexithiophene as donor; 1.2 V are reached when DIP is combined with poly(3‐hexylthiophene) (P3HT).