Control of open-circuit voltage in organic photovoltaic cells by inserting an ultrathin metal-phthalocyanine layer

The authors develop organic photovoltaic cells with multicharge separation (MCS) interfaces by inserting a very thin layer of metal phthalocyanine. The devices with MCS interface allow one to control short-circuit current density $(Jsc)$ and open-circuit voltage $(Voc)$⁠. The power conversion efficiency $(ηp)$ of the device with MCS interface (Cu-phthalocyanine/$C60andpentacene∕C60$⁠) is enhanced compared with that of the device with single charge separation interface (pentacene/$C60$⁠). The enhancement of $ηp$ is attributable to the increase in $Voc$ with maintaining the $Jsc$⁠. By using Zn-phthalocyanine, which possesses longer excited lifetime compared with Cu-phthalocyanine, both $Jsc$ and $Voc$ have been improved simultaneously and the $ηp$ reaches 2.04%.