AbstractThe fabrication of organic solar cells on paper substrate is attractive as it paves the way for roll‐to‐roll‐processed modules on more ecologically friendly substrates. A paper‐substrate solar‐cell process is successfully demonstrated. Commercially available paper with coatings from the polyvinyl family of materials is made suitable for electronic‐device fabrication. Smoothing layers of polyvinyl formal (PVF) with a knife‐edge coater give them an acceptable root mean square roughness of around 2.6 ± 0.2 nm. This paper is shown to be compatible with subsequent organic‐solar‐cell device fabrication with a variety of solvents including polar solvents. Top‐illuminated solar cells with blends of either poly(3‐hexylthiophene) and [6,6]‐phenyl C61 butyric acid methyl ester (PCBM), or poly({4,8‐bis[(2‐ethylhexyl)oxy]benzo[1,2‐b:4,5‐b′]dithiophene‐2,6‐diyl}{3‐fluoro‐2‐[(2‐ethylhexyl)carbonyl]thieno[3,4‐b]thiophenediyl}) and PCBM as photoactive layer having power conversion efficiencies up to 3.37% and 6.44%, respectively, are fabricated. A statistically significant number solar cells with different areas from multiple runs are fabricated and their solar cell parameters are analyzed and discussed. The results show strong promise for solar‐cell fabrication on environmentally friendly paper substrates.