Molecular materials have emerged as highly flexible platform for photovoltaic and light-harvesting applications. One of the most important challenges for this class of materials is the trapping of charge carriers in bound electron–hole pairs, which severely limits the free charge carrier generation. Here, we demonstrate a significant modification of the exciton dynamics in thin films of endohedral metallofullerene complexes upon alkali metal doping. For the exemplary case of Sc${}_3$N@C₈₀ thin films, we show that potassium doping results in an additional relaxation channel for the optically excited charge-transfer excitons that prevents the trapping of excitons in a long-lived Frenkel exciton-like state. Instead, potassium doping leads to an ultrafast exciton dissociation and most likely to the generation of free charge carriers. In this way, we propose alkali metal doping of molecular films as a novel approach to enhance the light-to-charge carrier conversion efficiency in photovoltaic molecular materials.

分子材料已成为光伏和光收集应用的高度灵活平台。这类材料最重要的挑战之一是在束缚电子 - 空穴对中捕获电荷载流子，这严重限制了自由电荷载流子的产生。在这里，我们展示了碱金属掺杂后内嵌金属富勒烯配合物薄膜中激子动力学的显着改变。对于 Sc 的示例${}_3$N@C ₈₀薄膜，我们表明钾掺杂导致光激发电荷转移激子的额外弛豫通道，防止激子在长寿命的 Frenkel 激子状状态中被俘获。相反，钾掺杂导致超快激子解离，并且最有可能产生自由电荷载流子。通过这种方式，我们提出了分子膜的碱金属掺杂作为一种提高光伏分子材料中光到电荷载流子转换效率的新方法。