The one-step condensation between the Green Fluorescence Protein (GFP) chromophore and 1H-imidazole-5-carbaldehyde catalyzed by ZnCl(2) proved to be a facile method to synthesize the red Kaede chromophore and its derivatives (1a-d, 2, and 3 > 70%), among which 1a then demonstrated its potential as a dye in solar cell, with a moderate conversion efficiency (eta) of 3.04%.