Transparent and flexible amorphous InZnAlO films grown by roll-to-roll sputtering for acidic buffer-free flexible organic solar cells

We report on transparent and flexible amorphous In-Zn-Al-O (a-IZAO) films prepared by roll-to-roll (RTR) sputtering for use as anodes in acidic buffer free flexible organic solar cells (FOSCs). The presence of Zn and Al structural stabilizers in the In2O3 matrix produced a completely amorphous structure with the high optical transmittance of 89.25% and the low resistivity of 2.123 x 10(-3) Omega-cm, as well as the high work function of 5.14 eV, making the a-IZAO films suitable for use as flexible anodes for FOSCs. In addition, the a-IZAO films showed no change in resistance (Delta R) during outer and inner bending fatigue tests due to their good mechanical flexibility. Relative to the power conversion efficiency (1.944%) of a PEDOT:PSS-based FOSCs, a FOSC fabricated by using an a-IZAO anode and without the use of acidic PEDOT:PSS buffer showed greater power conversion efficiency (2.509%), owing to the absence of interfacial reactions between the acidic PEDOT: PSS and the a-IZAO anode. (C) 2015 Elsevier B.V. All rights reserved.