Zarrabi Nasim, Yazmaciyan Aren, Meredith Paul, Kassal Ivan, Armin Ardalan
Department of Physics , Swansea University , Singleton Park , Swansea , Wales SA2 8PP , United Kingdom.
School of Mathematics and Physics , The University of Queensland , St. Lucia , QLD 4072 , Australia.
J Phys Chem Lett. 2018 Oct 18;9(20):6144-6148. doi: 10.1021/acs.jpclett.8b02484. Epub 2018 Oct 10.
The dynamics of exciton quenching are critical to the operational performance of organic optoelectronic devices, but their measurement and elucidation remain ongoing challenges. Here, we present a method for quantifying small photoluminescence quenching efficiencies of organic semiconductors under steady-state conditions. Exciton quenching efficiencies of three different organic semiconductors, PC70BM, P3HT, and PCDTBT, are measured at different bulk quencher densities under continuous low-irradiance illumination. By implementing a steady-state bulk-quenching model, we determine exciton diffusion lengths for the studied materials. At low quencher densities we find that a secondary quenching mechanism is in effect, which is responsible for approximately 20% of the total quenched excitons. This quenching mechanism is observed in all three studied materials and exhibits quenching volumes on the order of several thousand cubic nanometers. The exact origin of this quenching process is not clear, but it may be indicative of delocalized excitons being quenched prior to thermalization.
激子猝灭动力学对于有机光电器件的运行性能至关重要，但其测量和阐释仍然是持续存在的挑战。在此，我们提出一种在稳态条件下量化有机半导体微小光致发光猝灭效率的方法。在连续低辐照照明下，测量了三种不同有机半导体PC70BM、P3HT和PCDTBT在不同本体猝灭剂密度下的激子猝灭效率。通过实施稳态本体猝灭模型，我们确定了所研究材料的激子扩散长度。在低猝灭剂密度下，我们发现一种二级猝灭机制起作用，它约占总猝灭激子的20%。在所有三种研究材料中都观察到这种猝灭机制，并且其猝灭体积在数千立方纳米量级。这种猝灭过程的确切起源尚不清楚，但它可能表明离域激子在热化之前被猝灭。
