Temperature-Dependent Charge-Transfer-State Absorption and Emission Reveal the Dominant Role of Dynamic Disorder in Organic Solar Cells
Clemens Göhler, Maria Saladina, Yazhong Wang, Donato Spoltore, Johannes Benduhn, Karl Leo, Carsten Deibel
Abstract
In organic photovoltaics, the energetic characteristics of the charge-transfer state determine the device properties, and are defined by molecular interactions at the donor-acceptor interface. This study uses sensitive spectroscopy to investigate the roles of morphological disorder and molecular dynamics in charge-transfer states, which ultimately affect the open-circuit voltage. The authors model temperature-dependent data and find that dynamic, rather than static, disorder determines the optical properties of the charge-transfer states. Thus, to develop highly efficient organic solar cells, the intramolecular properties of the working materials should receive more attention.