Solution-processible Cd-doped ZnO nanoparticles as an electron transport layer to achieve high performance polymer solar cells through improve conductivity and light transmittance

In this work, electron transport layers (ETLs)with high charge transfer ability was fabricated by doping ZnO nanoparticles with different concentrations of cadmium. The performance for an inverted polymer solar cell based on PTB7-Th: PC 71 BM with 5% cadmium doping of zinc oxide nanoparticles (CZO) ETL is better than pure ZnO,which can enhance the short-circuit current ( J SC ), from 16.30 mA/cm 2 to 17.15 mA/cm 2 , the fill factor (FF) from 64.45% to 69.38%, power conversion efficiency（PCE）from 8.09% to 9.28%. It's consequence of performance stems from curbing interfacial charge recombination and effective charge extraction. Meanwhile, Taking a series of characterization methods, such as atomic force microscopy (AFM), the space charge limited current (SCLC), transmittance, the charge dissociation probabilities (P(E,T)) , photo-electrochemical impedance spectroscopy (EIS). The results indicate that the electrical conductivity and transmittance of the films are improved by incorporation of Cd in the ZnO film, restrained surface charge recombination and enhanced the electron-transport capability. Therefore, the ETL of Cd-doped will be an ideal candidate for future optoelectronic devices.