Through-space charge transfer within single-component organic crystal: visual detection and rational regulation

Abstract

Charge transfer (CT) could endow organic luminescent materials with many outstanding properties, particularly triplet harvesting for room-temperature phosphorescence (RTP), which has attracted extensive attention from scientists in recent years. Among them, through-space charge transfer (TSCT) was extensively investigated as a hot topic. However, detecting the existence of TSCT and adjusting it through rational methods are still huge challenges. Herein, we demonstrate a new strategy combining donor (PtzO) and accepter (BP) by a non-conjugated alkyl chain to obtain compound PtzO–3C–BP, successfully realizing TSCT-based RTP in the crystal state. In return, the RTP effect could act as a direct signal to indicate the strength of TSCT. Furthermore, compounds PtzO–nC–BP (n = 4–6) with changed alkyl chains are synthesized, to explore the semi-quantitative relation between TSCT-based phosphorescence performance and donor–accepter distance in the crystal state for a deeper understanding of TSCT.