Lee Taeho, Song Chang Eun, Lee Sang Kyu, Shin Won Suk, Lim Eunhee
Department of Chemistry, Kyonggi University, 154-42 Gwanggyosan-ro, Yeongtong-gu, Suwon 16227, Republic of Korea.
Energy Materials Research Center, Korea Research Institute of Chemical Technology (KRICT), 141 Gajeong-ro, Yuseong-gu, Daejeon 34114, Republic of Korea.
ACS Omega. 2021 Feb 9;6(7):4562-4573. doi: 10.1021/acsomega.0c04495. eCollection 2021 Feb 23.
Two nonfullerene small molecules, and , which have the same thiophene-benzothiadiazole-thiophene (TBTT) core flanked with butyloctyl (BO)- and octyl (O)-substituted rhodanines (RHs) at both ends, respectively, are developed as electron acceptors for organic solar cells (OSCs). The difference between the alkyl groups introduced into and strongly influence the intermolecular aggregation in the film state. Differential scanning calorimetry and UV-vis absorption studies reveal that exhibited stronger molecular aggregation behavior than . On the contrary, the material solubility is greatly improved by the introduction of a BO group in , and the inevitably low molecular interaction and packing ability of the as-cast film can be effectively increased by a solvent-vapor annealing (SVA) treatment. OSCs based on the two acceptors and PTB7-Th as a polymer donor are fabricated owing to their complementary absorption and sufficient energy-level offsets. The best power conversion efficiency of 8.33% is obtained with the SVA-treated device, where, together with a high open-circuit voltage of 1.02 V, the charge-carrier mobility and the short-circuit current density were greatly improved by the SVA treatment to levels comparable to those of the device because of the suppressed charge recombination and improved film morphology. In this work, the simultaneous improvement of both material solubility and device performance is achieved through alkyl side-chain engineering to balance the trade-offs among material solubility/crystallinity/device performance.
开发了两种非富勒烯小分子，分别为 和 ，它们具有相同的噻吩-苯并噻二唑-噻吩（TBTT）核，两端分别侧接丁基辛基（BO）-和辛基（O）-取代的罗丹宁（RH），用作有机太阳能电池（OSC）的电子受体。引入到 和 中的烷基差异强烈影响薄膜状态下的分子间聚集。差示扫描量热法和紫外-可见吸收研究表明， 表现出比 更强的分子聚集行为。相反，在 中引入BO基团极大地提高了材料的溶解性，并且通过溶剂蒸汽退火（SVA）处理可以有效提高铸膜态 的不可避免的低分子相互作用和堆积能力。基于这两种受体和作为聚合物供体的PTB7-Th制备了OSC，这是由于它们具有互补吸收和足够的能级偏移。经SVA处理的 器件获得了8.33%的最佳功率转换效率，其中，由于电荷复合受到抑制且薄膜形态得到改善，SVA处理使电荷载流子迁移率和短路电流密度大幅提高，达到了与 器件相当的水平，同时开路电压高达1.02 V。在这项工作中，通过烷基侧链工程实现了材料溶解性和器件性能的同时提高，以平衡材料溶解性/结晶度/器件性能之间的权衡。
