Doping-activated thermal polymorphic transition of luminescent organic crystals

Abstract

Herein, we propose an unprecedented doping strategy to activate thermal polymorphic transitions in organic molecular crystals. While the green-emissive crystal of mono(benzothienyl)benzothiadiazole remains unchanged upon direct heating, doping with only 0.3 mol% bis(benzothienyl) derivative affords an orange-emissive crystal that undergoes a thermal transition to another polymorph accompanied by luminescence switching.