ORGANIC MATERIAL UNDERGOING LIGHT-INDUCED PHASE TRANSITION
An organic material undergoing light-induced phase transition comprising a diheteroarylethene compound which in a crystalline state undergoes a photochromic reaction. The diheteroarylethene compound reversibly changes in color upon irradiation with light. It comes into a liquid phase state in the course of a change from a crystalline open-ring form to a crystalline closed - ring form or in the course of a change from a crystalline closed-ring form t o a crystalline open-ring form. The compound is usable in optical recording media, display panels, sensors, optical switch elements, etc. so as to take advantage of not only the color changing upon light irradiation but differences in refractive index, transmittance, etc. caused by phase changes .