LAUSR

Abstract Large scale organic semiconductor films with precisely-controlled thickness are highly demanded in photovoltaic and other applications. Yet it is still challenging to prepare such kinds of organic films with conventional solution-based techniques. Here we report a simple interfacial-assembling method to fabricate various films of organic semiconductors. Sub-square-meter sized organic films of Poly (3-hexylthiophene) (P3HT) and [6, 6]-phenyl-C61-butyric acid methyl ester (PC61BM) with controllable thicknesses from ~ 12 nm to ~ 140 nm were obtained. Under the guidance of an ultra-fast precursor film at the water-oil-air interface, the solution of P3HT and PC61BM quickly spread over the water surface in several seconds. After the evaporation of the solvent, a uniform thin film is formed with 100% utilization of the materials. This utilization indicates a power-per-weight of active materials fed as high as 152.09 W g−1, which is about ten times of P3HT:PC61BM-based solar cells prepared by conventional methods. In addition, the resultant films floating on the water surface are easily transferred to various water-insoluble substrates. The so-produced paper-based flexible photodetectors show good performances. This interfacial assembling strategy with general validity toward organic films is promising in future applications.