Binding energy of singlet excitons and charge transfer complexes in MDMO‐PPV:PCBM solar cells

The influence of an external electric field on the photoluminescence intensity of singlet excitons and charge transfer complexes is investigated for a poly[2‐methoxy‐5‐(3′,7′‐dimethyloctyloxy)‐1,4‐phenylenevinylene] (MDMO‐PPV) diode and a bulk heterojunction of the PPV in combination with [6,6]‐phenyl‐C61 butyric acid methylester (PCBM), respectively. The experimental data is related to the dissociation probability derived from the Onsager–Braun model. In this way, a lower limit for the singlet exciton binding energy of MDMO‐PPV is determined as $ (327 \pm 30) $ meV, whereas a significantly lower value of $ (203 \pm 18) $ meV is extracted for the charge transfer complex in a MDMO‐PPV:PCBM blend. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)