Solution-processed organic phototransistors based on controllable crystal growth of rubrene thin films with polymer-assisted layer

Crystalline rubrene films were fabricated by polymer-assisted layer in a sequential solution deposition process. Controllable crystal growth was achieved through varying the solution concentration of the polystyrene layers of the bilayer thin films. And the transitions from dendrites to spherulites were observed. The formation mechanism of rubrene crystals was proposed. Phototransistors based on rubrene thin film modified by PS-assisted layer showed a mobility of 1.67 x 10(-3)cm(2)/Vs, a photoresponsivity of 4.7 mu A/W, and a photosensitivity of 6900 under 200 mW/cm(2) light power conditions. This process provides a valuable platform for studying the organic crystal growth and its photoelectric properties.