We report on the photorefractive properties of thermally stable polymer composites based on the dye 2, N, N-dihexylamino-7-dicyanomethylidenyl-3,4,5,6,10-pentahydronaphthalene. At an applied field of 50 V/mu m, we have achieved a dynamic range of Delta n = 8.5X10(-3) and a net two-beam coupling gain of 202 cm(-1). The diffraction efficiency peaks at an applied field of 28 V/mu m, giving an external diffraction efficiency of 71%. (C) 1998 American Institute of Physics. [S0003-6951(98)04314-9].