Thermal treatment under reverse bias: Effective tool for polymer/fullerene bulk heterojunction solar cells

The effect of post-thermal treatment under reverse bias on the performance of bulk heterojunction photovoltaic cells based on poly[2-methoxy-5-(20-ethylhexyloxy)-p-phenylene vinylene] (MEH-PPV) and fullerene (C60) composites is investigated. The experimental results show that treated devices deliver increased short-circuit current density (Jsc) and conversion efficiency (ηp) values. Especially, for the device annealed under the bias of −6 V, the short-circuit current density (Jsc) and the conversion efficiency (ηp) are enhanced by a factor of 6 and 5.4, respectively. It is concluded that the enhancement of charge mobility induced by polymer chains modified orientation along the direction of electric field leads to a significant increase in the photovoltaic parameters.