Study of blocking effect of Cu-phthalocyanine layer in zinc oxide/pentacene/CuPc/C60/Al organic solar cells by electric field-induced optical second harmonic generation measurement

By employing electric-field-induced optical second-harmonic generation (EFISHG) measurement, we studied the blocking effect of sandwiched Cu-phthalocyanine (CuPc) layer on IZO/pentacene/Cu-phthalocyanine (CuPc)/C60/Al organic solar cells (OSCs). Results evidently showed that the Maxwell–Wagner type interfacial charging appears at both pentacene/CuPc and CuPc/C60 interfaces, depending on the CuPc layer thickness. When the thickness of CuPc layer was 8 nm, the charging at the two interfaces was significantly suppressed and the I–V characteristic was improved. CuPc layer is available as a blocking layer for the regulation of interfacial charging induced in IZO/pentacene/C60/Al organic solar cells (OSCs). The blocking effect of the CuPc layer was discussed on the basis of Maxwell–Wagner model analysis.

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► Interfacial charging appears at both pentacene/CuPc and CuPc/C60 interfaces.
► CuPc layer works as a blocking layer for the regulation of interfacial charging.
► The Maxwell–Wagner model well accounted for the results.