Marques Dos Santos John, Jagadamma Lethy Krishnan, Latif Najwa Mousa, Ruseckas Arvydas, Samuel Ifor D W, Cooke Graeme
School of Chemistry, University of Glasgow Joseph Black Building Glasgow G12 8QQ UK
Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St. Andrews St. Andrews, Fife KY16 9SS UK
RSC Adv. 2019 May 16;9(27):15410-15423. doi: 10.1039/c9ra01750j. eCollection 2019 May 14.
The study of small donor molecules as the active component of organic solar cells continues to attract considerable attention due to the range of advantages these molecules have over their polymeric counterparts. Here we report the synthesis and solar cell fabrication of three BODIPY small molecule donors. Two of the dyes feature triphenylamine and phenothiazine as donor units attached to the and α-positions of the BODIPY core (TPA-PTZ-DBP and PTZ-TPA-BDP). Additionally, we have synthesised a push-pull derivative featuring phenothiazine moieties in the α-positions and a nitrobenzene in the -position (N-TPA-BDP) in order to investigate what effect this type of functionalisation has on the photovoltaic properties compared to the other dyes. The optoelectronic properties were investigated and the dyes showed broad absorption in the near-infrared with high extinction coefficients. Electrochemical measurements indicated good reversibility for the dyes redox processes. In contrast with the all-donor functionalised systems, N-TPA-BDP demonstrated extensive HOMO-LUMO overlap by DFT. The dyes were investigated as donor molecules in bulk heterojunction solar cells along with PCBM, and under optimal donor to acceptor ratio PTZ-TPA-BDP showed the highest PCE of 1.62%. N-PTZ-BDP:PCBM was the only blend to further improve upon thermal annealing reaching the highest conversion efficiency among the dyes of 1.71%. A morphology comprised of finely mixed donor and acceptor components is observed for BHJ blends of each of the three donors at their optimum fullerene content. Upon thermal annealing, these morphological features remain mostly the same for PTZ-TPA-BDP:PCBM and TPA-PTZ-DBP:PCBM blends whereas for N-PTZ-BDP:PCBM the domains show a larger size. These dyes show that phenothiazine functionalisation of BODIPY is useful for solar cells because it gives strong and broad absorption extending to the near infra-red and materials with reversible redox properties - both of which are desirable for organic solar cells.
由于小分子供体分子相较于聚合物对应物具有一系列优势，因此将其作为有机太阳能电池的活性成分进行研究一直备受关注。在此，我们报告了三种BODIPY小分子供体的合成及太阳能电池制备。其中两种染料的特征是，三苯胺和吩噻嗪作为供体单元连接在BODIPY核的β和α位置（TPA-PTZ-DBP和PTZ-TPA-BDP）。此外，我们还合成了一种推拉衍生物，其α位置具有吩噻嗪部分，β位置具有硝基苯（N-TPA-BDP），以研究这种功能化类型与其他染料相比对光伏性能有何影响。研究了其光电性能，这些染料在近红外区域表现出宽泛的吸收，且具有高消光系数。电化学测量表明染料的氧化还原过程具有良好的可逆性。与全供体功能化体系不同，N-TPA-BDP通过密度泛函理论（DFT）显示出广泛的最高已占分子轨道（HOMO）-最低未占分子轨道（LUMO）重叠。这些染料与苯基-C61-丁酸甲酯（PCBM）一起作为本体异质结太阳能电池中的供体分子进行了研究，在最佳供体与受体比例下，PTZ-TPA-BDP的最高功率转换效率（PCE）为1.62%。N-PTZ-BDP:PCBM是唯一在热退火后进一步改善的共混物，在所有染料中达到了最高转换效率1.71%。在三种供体各自的最佳富勒烯含量下，观察到它们与PCBM的本体异质结共混物具有由精细混合的供体和受体成分组成的形态。热退火后，PTZ-TPA-BDP:PCBM和TPA-PTZ-DBP:PCBM共混物的这些形态特征基本保持不变，而对于N-PTZ-BDP:PCBM，其区域尺寸更大。这些染料表明，BODIPY的吩噻嗪功能化对太阳能电池很有用，因为它能产生延伸至近红外的强烈且宽泛的吸收，以及具有可逆氧化还原特性的材料——这两者都是有机太阳能电池所期望的。
