NOVELTY - Forming a photoactive layer (140), comprises: applying a composition containing first and second materials on a substrate (110) to form an intermediate layer supported by the substrate, where the first material is different from the second material; removing at least some of the second material from the intermediate layer to form a porous layer having pores; and disposing a third material in at least some of the pores of the porous layer.    USE - The photoactive layer is useful in an article (claimed). The method is useful to prepare a photoactive layer in suitable organic semiconductive devices, such as field effect transistors, photodetectors (e.g. infrared (IR) detectors), photovoltaic detectors, imaging devices (e.g. red, green and blue imaging devices for cameras or medical imaging systems), LEDs (e.g. organic LEDs or IR or near IR LEDs), lasing devices, conversion layers (e.g. layers that convert visible emission into IR emission), amplifiers and emitters for telecommunication (e.g. dopants for fibers), storage elements (e.g. holographic storage elements) and electrochromic devices (e.g. electrochromic displays).    ADVANTAGE - The intermediate layer can serve as a template to form a photoactive layer with a desired morphology by replacing one of the first and second semiconductor materials with a third semiconductor material. The morphology of the intermediate layer does not change substantially during any subsequent processes. The method allows the preparation of a heterojunction photoactive layer with a desired morphology even though the two semiconductor materials (e.g. two semiconductor materials that do not have sufficient solubility in a common solvent) contained in the photoactive layer would otherwise result in an unfavorable morphology.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for an article comprising: first and second electrodes; and a photoactive layer between the first and second electrodes, where the photoactive layer comprises first and second semiconductor materials, and the first and second semiconductor materials do not both have a solubility of at least 0.1 mg/ml in any solvent at 25 degrees C, and the article is configured as a photovoltaic cell (100).    DESCRIPTION OF DRAWING(S) - The figure shows a cross-sectional view of a photovoltaic cell.    Photovoltaic cell (100)    Substrate (110)    Electrode (120)    Hole carrier layer (130)    Photoactive layer. (140)