NOVELTY - A thiazole comonomer unit containing polymer (A1), comprises: a first comonomer repeat unit containing a thiazole moiety; and a second comonomer repeat unit different from the first comonomer repeat unit, where the second comonomer repeat unit not being a thiophene moiety or a fluorene moiety.    USE - In article comprising photovoltaic cell (claimed); in field effect transistors, photodetectors, photovoltaic detectors, imaging devices, light emitting diodes, lasing devices, conversion layers, amplifiers and emitters, storage elements, and electrochromic devices.    ADVANTAGE - The combinations of monomers for preparing polymers, have properties for use as charge carriers in the active layer of a photovoltaic cell. By incorporating the polymer (A1) into a photovoltaic cell, the current and efficiency of the cell can increase. The polymer containing a thiazole moiety can absorb light at a relatively long wavelength and have improved solubility in organic solvents. The polymer containing a thiazole moiety can be used to prepare an electron donor material with improved semiconductive properties. The photovoltaic cell containing the polymer can have a band gap that is relatively ideal for its intended purposes. The photovoltaic cell containing the polymer can have relatively fast and efficient transfer of an electron to an electron acceptor material, by which the lowest unoccupied molecular orbital (LUMO) of the donor is at least about 0.2 electron volt (e.g. at least about 0.3 electron volt) less negative than the conduction band of the electron acceptor material. The photovoltaic cell containing the polymer can have relatively fast charge separation, by which the charge mobility of the positive charge, or hole, is relatively high and falls within the range of 10-4 to 10-1 cm2/Vs.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for an article, comprising: a first electrode; a second electrode; and a photoactive material disposed between the first and second electrodes, where the photoactive material containing the polymer (A1); and the article is configured as a photovoltaic cell.