On the function of a bathocuproine buffer layer in organic photovoltaic cells

Abstract
The role of bathocuproine (BCP) buffer layer inserted between active layer and Al contact in photovoltaic cells based on phthalocyanine (Pc) and C 60 was investigated. Photoluminescence(PL) experiments show exciton quenching at the C 60 – Al interface to be strongly reduced by inserting BCP. Current-voltage characteristics of photovoltaic cells with planar geometry front electrode/ Pc ∕ C 60 ∕ BCP ∕ Al show that BCP dramatically improves electron transport out of the C 60 film into the Al electrode. The tenfold increase in power conversion efficiency ( η ) with BCP can mostly be attributed to the latter effect. BCP does not improve η in photovoltaic cells with blend film geometry front electrode/ Pc : C 60 ∕ Al .