Synthesis and characterization of cyano-substituted pyridine derivatives for applications as exciton blockers in photovoltaic devices
作者:Juanjuan You、Ming-Fai Lo、Weimin Liu、Tsz-Wai Ng、Shiu-Lun Lai、Pengfei Wang、Chun-Sing Lee
DOI:10.1039/c2jm15287h
日期:——
A new class of cyano-substituted pyridine derivatives have been synthesized and characterized. The relationship between their chemical structures, energy gap, energy levels, electron mobility and device performance was studied systematically by applying the new materials as EBL in standard CuPc/C60/EBL organic photovoltaic (OPV) devices. Their properties fulfill all the requirements for a good EBL material, such as a wide energy gap (Eg, 3.12–3.50 eV), a deep highest occupied molecular orbital (HOMO, 6.71–7.80 eV) energy level, a high electron mobility (in the order of 10−5 cm2 V−1 s−1) and a high glass transition temperature (Tg, 139–189 °C), thus most of them show performances surpassing that of BCP. In particular, one device shows an efficiency of 2.12% and a half-efficiency lifetime of 340 h, which are, respectively, 44% and more than 5 times better than those (1.47%, 60 h) of the BCP-based device. Furthermore, we found that the lowest unoccupied molecular orbital (LUMO) energy level of the EBL can also influence the leakage current and thus the efficiency of the OPV devices. It is expected that these studies would provide useful guidance for designing high-performance EBL materials.
我们合成并表征了一类新的氰基取代吡啶衍生物。通过将这些新材料用作标准 CuPc/C60/EBL 有机光伏(OPV)器件中的 EBL,系统地研究了它们的化学结构、能隙、能级、电子迁移率和器件性能之间的关系。这些材料的特性符合良好 EBL 材料的所有要求,例如宽能隙(Eg,3.12-3.50 eV)、深最高占位分子轨道(HOMO,6.71-7.80 eV)能级、高电子迁移率(10-5 cm2 V-1 s-1 量级)和高玻璃化转变温度(Tg,139-189 ℃),因此它们中的大多数都显示出超越 BCP 的性能。其中,一个器件的效率为 2.12%,半效率寿命为 340 小时,分别比基于 BCP 的器件(1.47%,60 小时)高出 44% 和 5 倍多。此外,我们还发现 EBL 的最低未占分子轨道(LUMO)能级也会影响漏电流,从而影响 OPV 器件的效率。预计这些研究将为设计高性能 EBL 材料提供有益的指导。