Asymmetric Self-Assembled Monolayer as Hole Transport Layer Enables Binary Organic Solar Cells Based on PM6: Y6 with Over 19% Efficiency

Open AccessCCS ChemistryRESEARCH ARTICLES21 Aug 2024Asymmetric Self-Assembled Monolayer as Hole Transport Layer Enables Binary Organic Solar Cells Based on PM6: Y6 with over 19% Efficiency Zekun Chen, Xiaojun Li, Shucheng Qin, Yufei Gong, Zhe Liu, Meng Yuan, TongLing Liang, Lei Meng and Yongfang Li Zekun Chen , Xiaojun Li , Shucheng Qin , Yufei Gong , Zhe Liu , Meng Yuan , TongLing Liang , Lei Meng and Yongfang Li Cite this: CCS Chemistry. 2024;0:1–24https://doi.org/10.31635/ccschem.024.202404707 SectionsSupplemental MaterialAboutPDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareFacebookTwitterLinked InEmail The Self-Assembled Monolayer (SAM) based on (2-(9H-carbazol-9-yl)ethyl) phosphonic acid (2PACz) derivatives are promising alternative to replace PEDOT:PSS for the application as hole transport layers (HTLs) in organic solar cells (OSCs). Herein, based on MeO-4PACz, two new molecules of MeOF-4PACz and F-4PACz were designed and synthesized by replacing one or two methoxy groups of MeO-4PACz with fluorine atoms respectively. The introduction of fluorine atoms enhances the dipole moments of SAMs, which is favorable for down-shifting the work function (WF) of ITO/SAM electrodes to achieve ideal energy level alignment with the HOMO energy level of the donor, and for increasing the intermolecular interaction to improve the arrangement of SAMs on the ITO surface. Compared with MeO-4PACz, the asymmetric molecule MeOF-4PACz with a methoxy substituent replaced by fluorine atom exhibits a more uniform distribution on the ITO surface, which effectively reduces the contact defects with the active layer and suppresses the nonradiative recombination. In addition, the deeper WF of ITO/MeOF-4PACz reduced the voltage losses. The suitable WF-compatibility and superior surface uniformity of the electrode of ITO/MeOF-4PACz than ITO/MeO-4PACz and ITO/F-4PACz lead to lower holeinjection barrier and suppressed interfacial non-radiative recombination of the OSCs. Consequently, the OSCs based on PM6:Y6 with MeOF-4PACz as HTL exhibits a substantial improvement in power conversion efficiency (PCE) from 17.11% for the device with PEDOT:PSS as HTL to 19.14%. Noteworthy, PM6:Y6 is currently the most representative active layer, and 19.14% is a record high efficiency for the binary OSCs based on PM6:Y6 so far. In addition, the PCE values of the OSCs based on PM6:BTP-eC9 and PM6:CH1007 with MeOF-4PACz as HTL were also significantly improved to 19.48% (certified as 19.36%) and 18.33% respectively, which indicates the broad compatibility of MeOF-4PACz HTL with various mainstream active layer systems of the OSCs. Overall, this work underscores the significant impact of designing and modifying molecular structure of the SAM HTLs on further improving photovoltaic performance of the OSCs. Download figure Download PowerPoint Previous articleNext article FiguresReferencesRelatedDetails Issue AssignmentNot Yet AssignedSupporting Information Copyright & Permissions© 2024 Chinese Chemical Society Downloaded 0 times PDF downloadLoading ...