Marin-Beloqui Jose M, Fallon Kealan J, Bronstein Hugo, Clarke Tracey M
Department of Chemistry , University College London , Christopher Ingold Building , London WC1H 0AJ , United Kingdom.
Department of Chemistry , University of Cambridge , Lensfield Road , Cambridge CB2 1EW , United Kingdom.
J Phys Chem Lett. 2019 Jul 5;10(13):3813-3819. doi: 10.1021/acs.jpclett.9b01264. Epub 2019 Jun 25.
The active layer of organic solar cells typically possesses a complex morphology, with amorphous donor/acceptor mixed domains present in addition to purer, more crystalline domains. These crystalline domains may represent an energy sink for free charges that aids charge separation and suppresses bimolecular recombination. The first step in exploiting this behavior is the identification and characterization of charges located in these different domains. Herein, the generation and recombination of both bulk and interfacial polarons are demonstrated in the dual electron donor/acceptor polymer XIND using transient absorption spectroscopy. The absorption spectra of XIND bulk polarons, present in pristine polymer domains, are clearly distinguishable from those of polarons present at the donor/acceptor interface. Furthermore, it is shown that photogenerated polarons are transferred from the interface to the bulk. These findings support the energy sink hypothesis and offer a way to maximize morphology relationships to enhance charge generation and suppress recombination.
有机太阳能电池的活性层通常具有复杂的形态，除了更纯净、更结晶的区域外，还存在非晶态供体/受体混合区域。这些结晶区域可能代表自由电荷的能量阱，有助于电荷分离并抑制双分子复合。利用这种行为的第一步是识别和表征位于这些不同区域的电荷。在此，使用瞬态吸收光谱法在双电子供体/受体聚合物XIND中证明了体相和界面极化子的产生和复合。原始聚合物区域中存在的XIND体相极化子的吸收光谱与供体/受体界面处存在的极化子的吸收光谱明显不同。此外，研究表明光生极化子从界面转移到体相。这些发现支持了能量阱假说，并提供了一种最大化形态关系以增强电荷产生和抑制复合的方法。
