Triplet polymer heterojunctions

Offermans et al. used several spectroscopic methods to study the formation and luminescence decay of exciplexes as a function of photoexcitation (of either polymer), and subsequent charge transfer at the heterojunction [229]. Exciplex formation was followed by a relaxation to the lower lying triplet state Ti of the MDMO-PPV. The energetic scheme is depicted in Fig. 48. 

Currently the best-performing heterojunction photovoltaic devices are made from blends of polythiophenes and PCBM [6,106]. Here, the charge-transfer states are stable with respect to triplet excitons, which comes at the cost of modest open-circuit voltages of 0.6V. Recent experimental evidence suggests that the high performance of PCBM polymer solar cells could also be attributed to the kinetic advantage in charge-transfer state separation that these cells have over those made from amorphous polymers. It is... 

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