Huang Jinzhen, Yu Huangzhong
School of Physics and Optoelectronics, South China University of Technology, 510640 Guangzhou, P. R. China.
State Key Lab of Subtropical Building Science, South China University of Technology, 510640 Guangzhou, P. R. China.
ACS Appl Mater Interfaces. 2021 Oct 6;13(39):46927-46937. doi: 10.1021/acsami.1c12326. Epub 2021 Sep 21.
The crystallinity of a nonfullerene small-molecule acceptor plays an important function in the bimolecular recombination and carrier transfer of polymer solar cells (PSCs). However, because of the competition between the donor (PBDB-T) and acceptor (ITIC) in processes of phase separation and crystallization, the PBDB-T preferentially forms a crystalline network, which limits the molecular diffusion of ITIC and leads to the weak crystallinity of ITIC, eventually restricting the photoelectric conversion efficiency (PCE) of PSCs. Therefore, in our work, a small-molecule biomaterial, Gly-His-Lys-Cu (SMBM GHK-Cu), is incorporated into binary PBDB-T:ITIC to construct a PBDB-T:ITIC:GHK-Cu ternary system. The addition of GHK-Cu increases ITIC crystallinity and promotes the formation in continuous single-phase domains of PBDB-T and ITIC, which creates an optimized bicontinuous network path to increase and balance charge transmission in PSCs. Meanwhile, GHK-Cu makes energy transfer from GHK-Cu to PBDB-T appreciably efficient, improving the photon capture and exciton-generation rate of PBDB-T. Moreover, it can form a complementary absorption spectrum with PBDB-T and ITIC, which enhances the PCE of ternary devices. Excitingly, the PCE of PSC-based PBDB-T:ITIC is enhanced from 10.28% to 12.07% via incorporating 0.1 wt % GHK-Cu into PBDB-T:ITIC, in which the enhanced open voltage () is 0.92 V, the short-circuit current () is 17.87 mA/cm, and the fill factor (FF) is 73.4%. Meanwhile, the PCE of PSC-based PM6:Y6 is also enhanced from 15.21% for a binary PSC to 17.11% for ternary PSC-based PM6:Y6:0.1 wt % GHK-Cu. This work shows that the cheap and environmentally friendly GHK-Cu has great potential for application in tuning the crystallinity and phase separation of the active layer.
非富勒烯小分子受体的结晶度在聚合物太阳能电池（PSC）的双分子复合和载流子转移中起着重要作用。然而，由于供体（PBDB-T）和受体（ITIC）在相分离和结晶过程中的竞争，PBDB-T优先形成结晶网络，这限制了ITIC的分子扩散并导致ITIC结晶度较弱，最终限制了PSC的光电转换效率（PCE）。因此，在我们的工作中，一种小分子生物材料甘氨酰-组氨酰-赖氨酸-铜（SMBM GHK-Cu）被引入二元体系PBDB-T:ITIC中，以构建PBDB-T:ITIC:GHK-Cu三元体系。GHK-Cu的加入提高了ITIC的结晶度，并促进了PBDB-T和ITIC在连续单相域中的形成，这创造了一条优化的双连续网络路径，以增加和平衡PSC中的电荷传输。同时，GHK-Cu使从GHK-Cu到PBDB-T的能量转移明显高效，提高了PBDB-T的光子捕获和激子产生率。此外，它可以与PBDB-T和ITIC形成互补吸收光谱，从而提高三元器件的PCE。令人兴奋的是，通过将0.1 wt%的GHK-Cu引入PBDB-T:ITIC，基于PSC的PBDB-T:ITIC的PCE从10.28%提高到了12.07%，其中增强后的开路电压（）为0.92 V，短路电流（）为17.87 mA/cm²，填充因子（FF）为73.4%。同时，基于PSC的PM6:Y6的PCE也从二元PSC的15.21%提高到了基于三元PSC的PM6:Y6:0.1 wt% GHK-Cu的17.11%。这项工作表明，廉价且环保的GHK-Cu在调节活性层的结晶度和相分离方面具有巨大的应用潜力。
