Short Excited-State Lifetimes Enable Photo-Oxidatively Stable Rubrene Derivatives

A series of rubrene derivatives were synthesized and the influence of the side group in enhancing photo-oxidative stability was evaluated. Photo-oxidation half-lives were determined via UV–vis absorption spectroscopy, which revealed thiophene containing derivatives to be the most stable species. The electron affinity of the compounds did not correlate with stability as previously reported in literature. Our work shows that shorter excited-state lifetimes result in increased photo-oxidative stability in these rubrene derivatives. These results confirm that faster relaxation kinetics out-compete the formation of reactive oxygen species that ultimately degrade linear oligoacenes. This report highlights the importance of using molecular design to tune excited-state lifetimes in order to generate more stable oligoacenes.本研究合成了一系列红荧烯（rubrene）衍生物，并评估了侧基对提升其光氧化稳定性的作用。通过紫外-可见吸收光谱法测定了各衍生物的光氧化半衰期，结果显示含噻吩（thiophene）基团的衍生物稳定性最优。本研究发现，化合物的电子亲和能与稳定性之间并不存在文献此前报道的相关性。我们的工作证实，在这类红荧烯衍生物中，更短的激发态寿命可提升光氧化稳定性；该结果验证了更快的弛豫动力学能够竞争性抑制活性氧物种的生成，而后者正是最终降解线性低并苯（linear oligoacenes）类化合物的关键因素。本报告强调了通过分子设计调控激发态寿命，以制备稳定性更优异的线性低并苯类化合物的重要性。