Xue Jingwei, Zhao Heng, Lin Baojun, Wang Yilin, Zhu Qinglian, Lu Guanyu, Wu Baohua, Bi Zhaozhao, Zhou Xiaobo, Zhao Chao, Lu Guanghao, Zhou Ke, Ma Wei
State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, China.
Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an, 710054, China.
Adv Mater. 2022 Aug;34(31):e2202659. doi: 10.1002/adma.202202659. Epub 2022 Jul 1.
Organic solar cells (OSCs) are promising candidates for next-generation photovoltaic technologies, with their power conversion efficiencies (PCEs) reaching 19%. However, the typically used spin-coating method, toxic halogenated processing solvents, and the conventional bulk-heterojunction (BHJ), which causes excessive charge recombination, hamper the commercialization and further efficiency promotion of OSCs. Here, a simple but effective dual-slot-die sequential processing (DSDS) strategy is proposed to address the above issues by achieving a continuous solution supply, avoiding the solubility limit of the nonhalogen solvents, and creating a graded-BHJ morphology. As a result, an excellent PCE of 17.07% is obtained with the device processed with o-xylene in an open-air environment with no post-treatment required, while a PCE of over 14% is preserved in a wide range of active-layer thickness. The unique film-formation mechanism is further identified during the DSDS processing, which suggests the formation of the graded-BHJ morphology by the mutual diffusion between the donor and acceptor and the subsequent progressive aggregation. The graded-BHJ structure leads to improved charge transport, inhibited charge recombination, and thus an excellent PCE. Therefore, the newly developed DSDS approach can effectively contribute to the realm of high-efficiency and eco-friendly OSCs, which can also possibly be generalized to other organic photoelectric devices.
有机太阳能电池（OSCs）是下一代光伏技术的有前途的候选者，其功率转换效率（PCEs）达到了19%。然而，通常使用的旋涂方法、有毒的卤化加工溶剂以及导致过度电荷复合的传统体相异质结（BHJ），阻碍了有机太阳能电池的商业化和进一步的效率提升。在此，提出了一种简单而有效的双狭缝模具连续加工（DSDS）策略，通过实现连续溶液供应、避免非卤化溶剂的溶解度限制以及创造分级BHJ形态来解决上述问题。结果，在露天环境中用邻二甲苯处理的器件获得了17.07%的优异PCE，无需后处理，同时在很宽的活性层厚度范围内PCE保持在14%以上。在DSDS加工过程中进一步确定了独特的成膜机制，这表明通过供体和受体之间的相互扩散以及随后的逐步聚集形成了分级BHJ形态。分级BHJ结构导致电荷传输改善、电荷复合受到抑制，从而具有优异的PCE。因此，新开发的DSDS方法可以有效地促进高效和环保型有机太阳能电池领域的发展，这也可能推广到其他有机光电器件。
