All-solution-processed inverted organic solar cell with a stacked hole-transporting layer

In this study, inverted organic solar cells (IOSCs) have been fabricated and characterized. A sol-gel zinc oxide (ZnO) film is used as a hole-blocking layer (HBL). Poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT:PSS) and copper phthalocyanine (CuPc) are used as a hole-transporting layer (HTL). The HBL, active layer, and HTL films are fabricated by spin-coating technique. The anode is fabricated from Ag nanoparticles by drop titration using a Pasteur burette. Experimental results show that the PEDOT: PSS/CuPc stacked HTL provides a stepwise hole-transporting energy diagram configuration, which subsequently increases the charge carrier transporting capability and extracts holes from the active layer to the anode. The characteristics of the IOSCs were optimized and exhibited an open-circuit voltage (V-oc), short-circuit current density (J(sc)), fill factor (FF), and power conversion efficiency (PCE) of 0.53V, 6.13mA/cm(2), 37.53%, and 1.24%, respectively, under simulated AM1.5G illumination of 100mW/cm(2). Hence, a solution process is feasible for fabricating low-cost and large-area solar energy devices. (C) 2014 The Japan Society of Applied Physics