Transparent conductive ZnO layers on polymer substrates: Thin film deposition and application in organic solar cells

• Aluminum doped and pure ZnO thin films are grown on polyethylene terephthalate.
• Growth parameters laser fluence, temperature, and gas pressure are optimized.
• AZO films on PET have high optical transmission and electrical conductance (FOM).
• Organic solar cells on PET using AZO as electron transport layer are made.
• Power conversion efficiency of these OSC devices is measured.

Aluminum doped ZnO (AZO) and pure ZnO thin films are grown on polymer substrates by pulsed-laser deposition and the optical, electrical, and structural film properties are investigated. Laser fluence, substrate temperature, and oxygen pressure are varied to obtain transparent, conductive, and stoichiometric AZO layers on polyethylene terephthalate (PET) that are free of cracks. At low fluence (1 J/cm2) and low pressure (10− 3 mbar), AZO/PET samples of high optical transmission in the visible range, low electrical sheet resistance, and high figure of merit (FOM) are produced. AZO films on fluorinated ethylene propylene have low FOM. The AZO films on PET substrates are used as electron transport layer in inverted organic solar cell devices employing P3HT:PCBM as photovoltaic polymer-fullerene bulk heterojunction.