TECHNOLOGY FOCUS - IMAGING AND COMMUNICATION - Preferred Components: The transparent ink has hydrophilicity. The refractive index of the transparent ink is greater than or equal to refractive index of the second substrate.    TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The solar cell further comprises a second PIN junction semiconductor layer under the first PIN junction semiconductor layer and a third PIN junction semiconductor layer under the second PIN junction semiconductor layer, where the first to third PIN junction semiconductor layers have the same structure as one another. The band gap energies are gradually increases from the first to third PIN junction semiconductor layer. Preferred Method: The step of forming the light collecting means on the second transparent electrode comprises: forming the self assembly monolayer on the second substrate; forming many ink droplets on the self assembly monolayer by jetting a transparent ink, where the transparent ink includes a first solvent having a first boiling point, a second solvent having a second boiling point lower than the first boiling point and a silicon oxide solid material dispersed in the first and second solvents; drying the ink droplets to form the microlenses; and attaching the second substrate to the second transparent electrode such that the microlenses contact the second transparent electrode. The self assembly monolayer is formed on an entire surface of the second substrate through one of a spin coating method, a slit coating method, a dip coating method, a spray coating method or a contact printing method. The step of drying the ink droplets includes one of a natural drying step, where the ink droplets are kept under a room temperature and the ink droplets are heated in a heat treatment apparatus under a temperature of 50-350 degrees C. The method further comprises hardening the ink droplets by heating the ink droplets in a heat treatment apparatus under a temperature of 50-350 degrees C. The concentration ratio of the first solvent to the second solvent is 0:100-10:90% or 90:10-100:0%.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The self assembly monolayer includes an alkyl siloxane material including one of octadecyltrichlorosilane, octadodecyltrichlorosilane or octadecyltrimethoxysilane data line having a straight line shape. The silicon oxide solid material has one of a nanoparticle shape or a molecular shape (tetraethoxysilane or tetrabutoxysilane). EXAMPLE - No suitable example given.