NOVELTY - Microstructured wavelength conversion film (100) comprises: a bottom surface; a top surface for receiving incident light, where the top surface comprises structures configured to increase the amount of photons emitted through the bottom surface; and a luminescent medium layer comprising a first optically transparent polymer matrix and at least one luminescent dye (201).    USE - The microstructured wavelength conversion film is useful in a solar energy conversion module (claimed), optical light collection systems, fluorescence-based solar collectors, fluorescence-activated displays and single-molecule spectroscopy.    ADVANTAGE - The microstructured wavelength conversion film: improves the performance of a solar energy conversion device (claimed) as compared to conventional wavelength conversion film without the microstructures; reduces the escaping loss of photons by increasing the total internal reflection and creating multiple reflection and refraction pathways which transmit more photons into the photoelectrode layer; provides the solar energy conversion device exhibiting improved light out-coupling efficiency; and is cost effective.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for:    (1) a solar energy conversion module (110) comprising a solar cell, and the microstructured wavelength conversion film over the solar cell;    (2) a method (M1) for improving the performance of a solar energy conversion device, comprising applying the microstructured wavelength conversion film onto a light incident surface for the solar cell; and    (3) a method (M2) for improving the performance of a solar energy conversion device, comprising incorporating the microstructured wavelength conversion film into the solar energy conversion device, so that the luminescent medium layer is between the solar cell and the light incident surface for the solar cell.    DESCRIPTION OF DRAWING(S) - The figure shows a solar cell having a wavelength conversion film applied on it.    Microstructured wavelength conversion film (100)    Solar energy conversion module (110)    Microstructured surface (200)    Luminescent dye (201)