Ross Russel B, Cardona Claudia M, Guldi Dirk M, Sankaranarayanan Shankara Gayathri, Reese Matthew O, Kopidakis Nikos, Peet Jeff, Walker Bright, Bazan Guillermo C, Van Keuren Edward, Holloway Brian C, Drees Martin
Georgetown University, 37th and O st. NW, Washington, District of Columbia 20057, USA.
Nat Mater. 2009 Mar;8(3):208-12. doi: 10.1038/nmat2379. Epub 2009 Feb 8.
So far, one of the fundamental limitations of organic photovoltaic (OPV) device power conversion efficiencies (PCEs) has been the low voltage output caused by a molecular orbital mismatch between the donor polymer and acceptor molecules. Here, we present a means of addressing the low voltage output by introducing novel trimetallic nitride endohedral fullerenes (TNEFs) as acceptor materials for use in photovoltaic devices. TNEFs were discovered in 1999 by Stevenson et al. ; for the first time derivatives of the TNEF acceptor, Lu(3)N@C(80), are synthesized and integrated into OPV devices. The reduced energy offset of the molecular orbitals of Lu(3)N@C(80) to the donor, poly(3-hexyl)thiophene (P3HT), reduces energy losses in the charge transfer process and increases the open circuit voltage (Voc) to 260 mV above reference devices made with [6,6]-phenyl-C(61)-butyric methyl ester (C(60)-PCBM) acceptor. PCEs >4% have been observed using P3HT as the donor material. This work clears a path towards higher PCEs in OPV devices by demonstrating that high-yield charge separation can occur with OPV systems that have a reduced donor/acceptor lowest unoccupied molecular orbital energy offset.
到目前为止，有机光伏（OPV）器件功率转换效率（PCE）的一个基本限制是由于供体聚合物与受体分子之间的分子轨道不匹配导致的低电压输出。在此，我们提出一种解决低电压输出的方法，即引入新型三金属氮化物内嵌富勒烯（TNEFs）作为用于光伏器件的受体材料。TNEFs于1999年由史蒂文森等人发现；首次合成了TNEF受体的衍生物Lu(3)N@C(80)，并将其集成到OPV器件中。Lu(3)N@C(80)分子轨道与供体聚（3-己基）噻吩（P3HT）之间的能量偏移减小，降低了电荷转移过程中的能量损失，并使开路电压（Voc）比使用[6,6]-苯基-C(61)-丁酸甲酯（C(60)-PCBM）受体制造的参考器件高出260 mV。使用P3HT作为供体材料时，已观察到PCE大于4%。这项工作通过证明在供体/受体最低未占据分子轨道能量偏移减小的OPV系统中可以发生高产率电荷分离，为提高OPV器件的PCE开辟了一条道路。
