Photopolymerization of a material containing liquid crystalline monomer was improved through the addition of a trithiocarbonate: EtO2CCH2SC(S)SCH2CO2Et. The electrically switchable holographic gratings showed increased efficiency, uniformity, and reproducibility. The mechanism of action of the trithiocarbonate was elucidated by the holographic results, along with results from initiator bleaching experiments, concentration studies, addition and in-situ generation of trithiocarbonate-trapped radicals, EPR studies, cyclic voltammetry measurements, and determination of diffraction grating exposure profiles. This additive was shown to simultaneously promote and inhibit the photopolymerization process, but not through the traditional RAFT (reversible addition fragmentation transfer) mechanism.