Ian Wark Laboratory, CSIRO Materials Science & Engineering , Clayton South, Victoria 3169 Australia.
J Am Chem Soc. 2014 Apr 23;136(16):6049-55. doi: 10.1021/ja500935d. Epub 2014 Apr 14.
Extensive efforts have been made to develop novel conjugated polymers that give improved performance in organic photovoltaic devices. The use of polymers based on alternating electron-donating and electron-accepting units not only allows the frontier molecular orbitals to be tuned to maximize the open-circuit voltage of the devices but also controls the optical band gap to increase the number of photons absorbed and thus modifies the other critical device parameter-the short circuit current. In fact, varying the nonchromophoric components of a polymer is often secondary to the efforts to adjust the intermolecular aggregates and improve the charge-carrier mobility. Here, we introduce an approach to polymer synthesis that facilitates simultaneous control over both the structural and electronic properties of the polymers. Through the use of a tailored multicomponent acceptor-donor-acceptor (A-D-A) intermediate, polymers with the unique structure A-D1-A-D2 can be prepared. This approach enables variations in the donor fragment substituents such that control over both the polymer regiochemistry and solubility is possible. This control results in improved intermolecular π-stacking interactions and therefore enhanced charge-carrier mobility. Solar cells using the A-D1-A-D2 structural polymer show short-circuit current densities that are twice that of the simple, random analogue while still maintaining an identical open-circuit voltage. The key finding of this work is that polymers with an A-D1-A-D2 structure offer significant performance benefits over both regioregular and random A-D polymers. The chemical synthesis approach that enables the preparation of A-D1-A-D2 polymers therefore represents a promising new route to materials for high-efficiency organic photovoltaic devices.
人们已经付出了大量努力来开发新型共轭聚合物，以提高有机光伏器件的性能。使用基于交替给体和受体单元的聚合物不仅可以调整前沿分子轨道以最大化器件的开路电压，还可以控制光学带隙以增加吸收的光子数量，从而改变其他关键器件参数-短路电流。事实上，改变聚合物的非发色团部分通常次于调整分子间聚集体和提高电荷载流子迁移率的努力。在这里，我们介绍了一种聚合物合成方法，该方法可以同时控制聚合物的结构和电子性质。通过使用定制的多组分给体-受体-给体（A-D-A）中间体制备了具有独特结构 A-D1-A-D2 的聚合物。这种方法可以改变供体片段的取代基，从而可以控制聚合物的区域化学和溶解性。这种控制导致增强的分子间π堆积相互作用，从而提高电荷载流子迁移率。使用 A-D1-A-D2 结构聚合物的太阳能电池显示出短路电流密度是简单随机类似物的两倍，同时仍保持相同的开路电压。这项工作的关键发现是，具有 A-D1-A-D2 结构的聚合物在区域规整和随机 A-D 聚合物方面都具有显著的性能优势。因此，能够制备 A-D1-A-D2 聚合物的化学合成方法代表了用于高效有机光伏器件的材料的有前途的新途径。
