Versatility of solution-processing strategy based on the simultaneous rather than additive deposition of different functional molecules is discussed. It is shown that spin-cast polymer blends result in films with domains that could form elements with complementary functions of (i) solar cells, (ii) electronic circuitries, and (iii) test plates for protein micro-arrays: Alternating layers, rich in electron-donating polyfluorene and electron-accepting fullerene derivative, result in optimized solar power conversion. Surface patterns, made by soft lithography, align conductive paths of conjugated poly(3-alkylthiophene) in dielectric polystyrene. Proteins, preserving their biologically activity, are adsorbed to hydrophobic domains of polystyrene in hydrophilic matrix of poly(ethylene oxide). The authors report the research progress on structure formation in three polymer blend families, resulting in films with complementary elements for electronics and biotechnology. Blend film structures are determined with secondary ion mass spectrometry, atomic force microscopy, and fluorescence microscopy. In addition, the authors present recent results on (i) structure formation in fullerene derivative/poly(3-alkylthiophene) blends intended for solar cells, (ii) 3-dimensional SIMS imaging of conductive paths of poly(3-alkylthiophene) in dielectric polystyrene, (iii) test plates for multiprotein micro-arrays fabricated with blend films of hydrophobic polystyrene and thermoresponsive poly(N-isopropylacrylamide).