Predicting reverse intersystem crossing (RISC) rates is crucial for designing thermally activated delayed fluorescence (TADF) materials. A new method has been developed to quantitatively predict RISC rates by considering the spin–vibronic coupling mechanism. By expanding spin–orbit and non-Born–Oppenheimer terms to second order, the method integrates these into the Golden Rule rate under the Condon approximation. This allows for direct time-domain rate equation solutions using a correlation function approach. The method distinguishes between first-order direct spin–orbit coupling and second-order spin–vibronic coupling contributions to the RISC rate. Applied to a representative TADF system, the method shows that while spin–vibronic coupling is substantial, it is not dominant, especially with a small triplet–singlet energy gap. This approach can aid in designing new organic TADF molecules by elucidating the physical background of efficient nonradiative transitions.-Journal cover design by scapiens
[Scientific Journal cover design] Low-Thermal-Budget Fluorite-Structure Ferroelectrics for Future Electronic Device Applications
In article number 2100028, Jiyoung Kim, Si Joon Kim, and their team review key factors involved in developing fluorite-structure ferroelectrics
