College of Polymer Science and Polymer Engineering, Department of Polymer Engineering, The University of Akron, Akron, OH 44325, USA.
Center for Polymers and Organic Solids, University of California, Santa Barbara, CA 931006, USA.
Chem Soc Rev. 2016 Aug 22;45(17):4825-46. doi: 10.1039/c5cs00650c.
In order to develop high performance polymer solar cells (PSCs), full exploitation of the sun-irradiation from ultraviolet (UV) to near infrared (NIR) is one of the key factors to ensure high photocurrents and thus high efficiency. In this review, five of the effective design rules for approaching LBG semiconducting polymers with high molar absorptivity, suitable energy levels, high charge carrier mobility and high solubility in organic solvents are overviewed. These design stratagems include fused heterocycles for facilitating π-electron flowing along the polymer backbone, groups/atoms bridging adjacent rings for maintaining a high planarity, introduction of electron-withdrawing units for lowering the bandgap (Eg), donor-acceptor (D-A) copolymerization for narrowing Eg and 2-dimensional conjugation for broadened absorption and enhanced hole mobility. It has been demonstrated that LBG semiconducting polymers based on electron-donor units combined with strong electron-withdrawing units possess excellent electronic and optic properties, emerging as excellent candidates for efficient PSCs. While for ultrasensitive photodetectors (PDs), which have intensive applications in both scientific and industrial sectors, sensing from the UV to the NIR region is of critical importance. For polymer PDs, Eg as low as 0.8 eV has been obtained through a rational design stratagem, covering a broad wavelength range from the UV to the NIR region (1450 nm). However, the response time of the polymer PDs are severely limited by the hole mobility of LBG semiconducting polymers, which is significantly lower than those of the inorganic materials. Thus, further advancing the hole mobility of LBG semiconducting polymers is of equal importance as broadening the spectral response for approaching uncooled ultrasensitive broadband polymer PDs in the future study.
为了开发高性能聚合物太阳能电池（PSC），充分利用从紫外（UV）到近红外（NIR）的太阳辐射是确保高电流和因此高效率的关键因素之一。在这篇综述中，综述了五种有效的设计规则，用于接近具有高摩尔吸收率、合适能级、高电荷载流子迁移率和高有机溶剂溶解度的 LBG 半导体聚合物。这些设计策略包括促进聚合物主链中π电子流动的稠合杂环、用于保持高平面性的相邻环之间的基团/原子桥接、引入吸电子单元以降低带隙（Eg）、供体-受体（D-A）共聚以缩小 Eg 以及 2 维共轭以拓宽吸收和增强空穴迁移率。已经证明，基于电子供体单元与强吸电子单元的 LBG 半导体聚合物具有优异的电子和光学性能，是高效 PSC 的优秀候选材料。而对于超灵敏光电探测器（PD），它在科学和工业领域都有广泛的应用，从 UV 到 NIR 区域的感应非常重要。对于聚合物 PD，通过合理的设计策略，Eg 低至 0.8 eV，覆盖了从 UV 到 NIR 区域（1450nm）的宽波长范围。然而，聚合物 PD 的响应时间受到 LBG 半导体聚合物空穴迁移率的严重限制，其显著低于无机材料。因此，进一步提高 LBG 半导体聚合物的空穴迁移率与拓宽光谱响应对于未来研究中接近无冷却超灵敏宽带聚合物 PD 同样重要。
