Communication: Amorphous organic photorefractive materials, which are useful for reversible holographic applications such as real-time optical processing and holographic data storage, have excellent performance but limited shelf life, often owing to the crystallization of one of the components. A technique is presented for improving the long-term stability of composites based on poly(N-vinylcarbazole) that uses mixtures of two isomeric electrooptically active chromophores. The shelf-life is shown to be significantly increased and the photorefractive device performance as good as that of the best materials known previously.