General behavior of ultrastability and anisotropic molecular packing in co-deposited organic semiconductor glass mixtures

Vapor-deposited glass mixtures of organic semiconductors serve as active layers in organic electronic devices. Here, we study the stability and anisotropic molecular packing of six co-deposited 50:50 organic semiconductor glass mixtures. The results show that all six binary systems exhibit highly enhanced kinetic stability and significantly reduced enthalpy when deposited at 0.78-0.88T_g,mixture. Furthermore, for a given binary system, the birefringence of the PVD glass mixture can be predicted from the temperature-dependent birefringence of the pure compounds. Our findings provide guidance for producing organic semiconductor glass mixtures with enhanced stability and desired structure, which has important implications for design of novel electronic devices with longer device lifetime and higher operational efficiencies.