Sonochemistry-synthesized CuO nanoparticles as an anode interfacial material for efficient and stable polymer solar cells

Abstract

Solution-processible copper oxide (CuO) nanoparticles have been synthesized via sonochemistry. Colloidal crystalline CuO nanoparticles with diameters of 3–12 nm were obtained from the CuCl₂ metal salt at low temperature under ultrasound irradiation. The solution-processible CuO nanoparticles are applied as an anode buffer layer in a PCDTBT:PC₇₁BM bulk heterojunction solar cell to substitute the commonly used hygroscopic PEDOT:PSS. It is found that UV–ozone treatment increases the work function of the CuO buffer layer from −4.7 to −5.4 eV, facilitating the interfacial contact and hole extraction. The UVO-treated CuO-based solar cells show enhanced fill factor and photocurrent, resulting in an increased photovoltaic performance from 6.00% to 6.44% in comparison to the PEDOT:PSS-based solar cells. Moreover, the solar cells with a CuO buffer layer show better ambient stability than those with a PEDOT:PSS buffer layer. The facile preparation of solution-processed CuO and effectiveness in polymer solar cells render it a promising anode interfacial material for solution-processed flexible polymer solar cells.