The self-assembled monolayer(SAM)based on(2-(9H-carbazol-9-yl)ethyl)phosphonic acid(2PACz)deri-vatives is a promising alternative to poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate)(PEDOT:PSS)for application t...The self-assembled monolayer(SAM)based on(2-(9H-carbazol-9-yl)ethyl)phosphonic acid(2PACz)deri-vatives is a promising alternative to poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate)(PEDOT:PSS)for application to 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 to downshifting the work function(WF)of indium tin oxide(ITO)/SAM electrodes to achieve ideal energy-level alignment with the highest occupied molecular orbital(HOMO)energy level of the donor,and for increasing the intermolecular interaction that improves the arrangement of SAMs on the ITO surface.Compared with MeO-4PACz,the asymmetric molecule MeOF-4PACz with a methoxy substituent replaced by a 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 reduces the voltage losses.The suitable WF compatibility and superior surface uniformity of the electrode of ITO/MeOF-4PACz to ITO/MeO-4PACz and ITO/F-4PACz lead to a lower hole-injection barrier and suppressed interfacial nonradiative recombination of the OSCs.Consequently,the OSCs based on PM6:Y6 with MeOF-4PACz as HTL exhibit a substantial improvement in power conversion efficiency(PCE)from 17.11%for the device with PEDOT:PSS as HTL to 19.14%.It is worth noting that 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 are 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 the molecular structure of the SAM HTLs on further improving the photovoltaic performance of OSCs.展开更多
基金supported by the National Key Research and Development Program of China(grant no.2019YFA0705900)the National Natural Science Foundation of China(grant nos.52203248,52103243,52173188)+3 种基金the Key Research Program of the Chinese Academy of Sciences(grant no.XDPB13)the Strategic Priority Research Program of the Chinese Academy of Sciences(grant no.XDB 0520102)the Basic and Applied Basic Research Major Program of Guangdong Province(grant no.2019B030302007)the Beijing National Laboratory for Molecular Science(grant no.2019BMS20017)。
文摘The self-assembled monolayer(SAM)based on(2-(9H-carbazol-9-yl)ethyl)phosphonic acid(2PACz)deri-vatives is a promising alternative to poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate)(PEDOT:PSS)for application to 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 to downshifting the work function(WF)of indium tin oxide(ITO)/SAM electrodes to achieve ideal energy-level alignment with the highest occupied molecular orbital(HOMO)energy level of the donor,and for increasing the intermolecular interaction that improves the arrangement of SAMs on the ITO surface.Compared with MeO-4PACz,the asymmetric molecule MeOF-4PACz with a methoxy substituent replaced by a 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 reduces the voltage losses.The suitable WF compatibility and superior surface uniformity of the electrode of ITO/MeOF-4PACz to ITO/MeO-4PACz and ITO/F-4PACz lead to a lower hole-injection barrier and suppressed interfacial nonradiative recombination of the OSCs.Consequently,the OSCs based on PM6:Y6 with MeOF-4PACz as HTL exhibit a substantial improvement in power conversion efficiency(PCE)from 17.11%for the device with PEDOT:PSS as HTL to 19.14%.It is worth noting that 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 are 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 the molecular structure of the SAM HTLs on further improving the photovoltaic performance of OSCs.
