High‐Resolution Afterglow Patterning Using Cooperative Vapo‐ and Photo‐Stimulation

Abstract

Bright afterglow room‐temperature phosphorescence (RTP) soon after ceasing excitation is a promising technique for greatly increasing anti‐counterfeiting capabilities. The development of a process for rapid high‐resolution afterglow patterning of crystalline materials can improve both high‐speed fabrication of anti‐counterfeiting afterglow media and stable afterglow readout compared with those achieved with amorphous materials. Here, the high‐resolution afterglow patterning of crystalline materials via cooperative organic vapo‐ and photo‐stimulation is reported. A single crystal of (S)‐(−)−2,2’‐bis(diphenylphosphino)−5,5’,6,6’,7,7’8,8’‐octahydro‐1,1’‐binaphthyl [(S)‐H8‐BINAP] doped with (S)‐(−)−2,2’‐bis(diphenylphosphino)−1,1’‐binaphthyl [(S)‐BINAP] shows green afterglow RTP. Crystals of (S)‐BINAP‐doped (S)‐H8‐BINAP changed to an amorphous state with no afterglow capability on weak continuous photoirradiation under dichloromethane (DCM) vapor. Photoirradiation induced oxidation of the (S)‐H8‐BINAP host molecule in the crystal. The oxidized (S)‐H8‐BINAP forms on the crystal surface strongly interacted with DCM molecules, which induces melting of the (S)‐BINAP‐doped (S)‐H8‐BINAP crystal and trigger formation of an amorphous state without an afterglow capability. High‐resolution afterglow patterning of the crystalline film is rapidly achieved by using cooperative organic vapo‐ and photo‐stimulation. In addition to the benefit of rapid afterglow patterning, the formed afterglow images of the crystalline film can be repeatedly read out under ambient conditions without DCM vapor.