Ompong David, Singh Jai
School of Engineering and IT, Faculty of EHSE, Charles Darwin University, Darwin, NT 0909 (Australia).
Chemphyschem. 2015 Apr 27;16(6):1281-5. doi: 10.1002/cphc.201402720. Epub 2015 Mar 3.
We derived new expressions for the diffusion length of singlet and triplet excitons by using the Föster and Dexter transfer mechanisms, respectively, and have found that the diffusion lengths of singlet and triplet excitons are comparable. By using the Langevin recombination theory, we derived the rate of recombination of dissociated free charges into their excitonic states. We found that in some organic polymers the probabilities of recombination of free charge carriers back into the singlet and triplet states are approximately 65.6 and 34.4 %, respectively, indicating that Langevin-type recombination into triplet excitons in organic semiconductors is less likely. This implies that the creation of triplet excitons may be advantageous in organic solar cells, because this may lead to dissociated free charge carriers that can be collected at their respective electrodes, which should result in better conversion efficiency.
我们分别利用福斯特（Föster）和德克斯特（Dexter）转移机制推导了单线态和三线态激子扩散长度的新表达式，并且发现单线态和三线态激子的扩散长度相当。通过使用朗之万复合理论，我们推导了离解的自由电荷复合为激子态的速率。我们发现，在一些有机聚合物中，自由电荷载流子复合回单线态和三线态的概率分别约为65.6%和34.4%，这表明在有机半导体中，朗之万型复合为三线态激子的可能性较小。这意味着三线态激子的产生在有机太阳能电池中可能具有优势，因为这可能会导致离解的自由电荷载流子，它们可以在各自的电极处被收集，这应该会带来更高的转换效率。
