The working mechanism of organic photovoltaic cell by using copper phthalocyanine as exciton blocking layer

We demonstrate the working mechanism of organic photovoltaic (OPV) cell with copper phthalocyanine (CuPc) as exciton blocking layer (EBL). The new EBL material CuPc, commonly has been used as electron donor in the organic solar cells due to its electron-donating and hole-transporting properties. But here we proves that the α-polymorph CuPc layer can transfer electrons to Al cathode through the half-filled b1g level, this mechanism is different from that of general EBL material with larger band gap and electron-transporting property, which is based on damage states induced by the heat of evaporating Al.

Schematic energy-level and proposed PV process for double-heterostructure PV devices using CuPc using as the exciton blocking layer with the thickness of (a) 10 nm and (b) 20 nm, respectively. Holes are shown as open circles and electrons as filled circles.Figure optionsDownload as PowerPoint slideHighlights
► CuPc layer is adopted as the EBL for organic photovoltaic cells.
► α-polymorph is found in the thermal evaporated CuPc EBL.
► Electrons are collected via the half-filled b1g level of the α-polymorph CuPc EBL.
► This mechanism is different from that of the general EBL materials.