The stability of organic solar cells(OSCs)remains a major concern for their ultimate industrialization due to the photo,oxygen,and water susceptibility of organic photoactive materials.Usually,antioxidant additives ar...The stability of organic solar cells(OSCs)remains a major concern for their ultimate industrialization due to the photo,oxygen,and water susceptibility of organic photoactive materials.Usually,antioxidant additives are blended as radical scavengers into the active layer.However,it will induce the intrinsic morphology instability and adversely affect the efficiency and long-term stability.Herein,the antioxidant dibutylhydroxytoluene(BHT)group has been covalently linked onto the side chain of benzothiadiazole(BT)unit,and a series of ternary copolymers D18-Cl-BTBHTx(x=0,0.05,0.1,0.2)with varied ratio of BHT-containing side chains have been synthesized.It was found that the introduction of BHT side chains would have a negligible effect on the photophysical properties and electronic levels,and the D18-Cl-BTBHT0.05:Y6-based OSC achieved the highest power conversion efficiency(PCE)of 17.6%,which is higher than those based active layer blended with BHT additives.More importantly,the unencapsulated device based on D18-Cl-BTBHTx(x=0.05,0.1,0.2)retained approximately 50%of the initial PCE over 30 hours operation under ambient conditions,significantly outperforming the control device based on D18-Cl(90%degradation in PCE after 30 h).This work provides a new structural design strategy of copolymers for OSCs with simultaneously improved efficiency and stability.展开更多
Under the mild condition a new ternary rare earth complex Eu （ DBM ）2MA · 2H2O [ DBM： C6H5COCHCOC6H5; MA： CH2C（CH3）COO^- ] was synthesized by the reaction of EuCl3 with dibenzoylmethane and methacrylate in ...Under the mild condition a new ternary rare earth complex Eu （ DBM ）2MA · 2H2O [ DBM： C6H5COCHCOC6H5; MA： CH2C（CH3）COO^- ] was synthesized by the reaction of EuCl3 with dibenzoylmethane and methacrylate in alcohol. A new bonded copolymer Eu（DBM）2MA-MMA was prepared by copolymerization of the Eu（DBM）2MA·2H2O complex with methyl methacrylate（MMA） monomer using AIBN as an initiator. The composition, structure and fluorescence properties of the complex and copolymer were characterized by means of elemental analysis, complex titration, IR, UV-VIS and fluorescent spectra. The thermal stability, glass temperature and average molecular weight of the copolymer Eu（DBM）2MA-MMA were determined by TG-DTA, DSC and GPC, respectively. The research results show that both of the ternary rare earth complex and the copolymer can emit strong Eu（Ⅲ） fluorescence at 613 nm.展开更多
We use a Monte Carlo method to study the phase and interracial behaviors of A-b-B diblocks in a blend of homopolymers, A and B, which are confined between two asymmetric hard and impenetrable walls. Our results show t...We use a Monte Carlo method to study the phase and interracial behaviors of A-b-B diblocks in a blend of homopolymers, A and B, which are confined between two asymmetric hard and impenetrable walls. Our results show that, when the interaction strength is weak, the block copolymers are uniformly distributed in the ternary mixtures under considered concentrations. Under strong interaction strength, distribution region of the block copolymers changes from a single smooth interface to a curved interface or multi-layer interface in the ternary mixtures. Furthermore, our findings show that with increasing volume fraction of A-b-B diblock copolymer （φc）, copolymer profiles broaden while φc ≥ 0.4, a lamellar phase is formed and by further increasing φc, more thinner layers are observed. Moreover, the results show that, with the increase of φc, the phase interface first gradually transforms from plane to a curved surface rather than micelle or lamellar phase while with the increase of the interaction between A and B segments （CAB）, the copolymer chains not only get stretched in the direction perpendicular to the interface, but also are oriented. The simulations also reveal that the difference between symmetric and asymmetric copolymers is negligible in statistics if the lengths of two blocks are comparable.展开更多
To achieve high-efficiency polymer solar cells(PSCs),it is not only important to develop high-performance small molecule acceptors(SMAs)but also to find a matching polymer donor to achieve optimal morphology and match...To achieve high-efficiency polymer solar cells(PSCs),it is not only important to develop high-performance small molecule acceptors(SMAs)but also to find a matching polymer donor to achieve optimal morphology and matching electronic properties.Currently,state-of-the-art SMAs mostly rely on a donor polymer named PM6.However,as the family of SMAs continues to expend,PM6 may not be the perfect polymer donor due to the requirement of energy level matching.In this work,we tune the energy level of PM6 via the strategy of ternary copolymerization.We achieve two donor polymers(named PL-1 and PL-2)with upshifted HOMO(the highest occupied molecular orbital)energy level(compared with PM6),and can thus match with the SMAs with upshifted HOMO energy levels compared with Y6.These two copolymers exhibit slightly higher order of molecular packing and similar charge transport properties,which demonstrate that the method of ternary copolymerization can fine tune the HOMO level of donor polymers,while the morphology and mobility of the blend film remain mostly unaffected.Among them,the best device based on PL-1:Y6 exhibits power conversion efficiencies(PCEs)of 16.37%with lower open circuit voltage(Voc)but higher short circuit current voltage(Jsc)and fill factor(FF)than that of the device based on PM6:Y6.This work provides an effective approach to find polymer matches for the SMAs with upshifted HOMO levels.展开更多
基金This work was financially supported by National Key Research and Development Program of China(No.2019YFA0705900)funded by MOSTthe Basic and Applied Basic Research Major Program of Guangdong Province(No.2019B030302007)+1 种基金the National Natural Science Foundation of China(No.U21A6002)Guangdong-Hong Kong-Macao Joint Laboratory of Optoelectronic and Magnetic Functional Materials(No.2019B121205002).
文摘The stability of organic solar cells(OSCs)remains a major concern for their ultimate industrialization due to the photo,oxygen,and water susceptibility of organic photoactive materials.Usually,antioxidant additives are blended as radical scavengers into the active layer.However,it will induce the intrinsic morphology instability and adversely affect the efficiency and long-term stability.Herein,the antioxidant dibutylhydroxytoluene(BHT)group has been covalently linked onto the side chain of benzothiadiazole(BT)unit,and a series of ternary copolymers D18-Cl-BTBHTx(x=0,0.05,0.1,0.2)with varied ratio of BHT-containing side chains have been synthesized.It was found that the introduction of BHT side chains would have a negligible effect on the photophysical properties and electronic levels,and the D18-Cl-BTBHT0.05:Y6-based OSC achieved the highest power conversion efficiency(PCE)of 17.6%,which is higher than those based active layer blended with BHT additives.More importantly,the unencapsulated device based on D18-Cl-BTBHTx(x=0.05,0.1,0.2)retained approximately 50%of the initial PCE over 30 hours operation under ambient conditions,significantly outperforming the control device based on D18-Cl(90%degradation in PCE after 30 h).This work provides a new structural design strategy of copolymers for OSCs with simultaneously improved efficiency and stability.
文摘Under the mild condition a new ternary rare earth complex Eu （ DBM ）2MA · 2H2O [ DBM： C6H5COCHCOC6H5; MA： CH2C（CH3）COO^- ] was synthesized by the reaction of EuCl3 with dibenzoylmethane and methacrylate in alcohol. A new bonded copolymer Eu（DBM）2MA-MMA was prepared by copolymerization of the Eu（DBM）2MA·2H2O complex with methyl methacrylate（MMA） monomer using AIBN as an initiator. The composition, structure and fluorescence properties of the complex and copolymer were characterized by means of elemental analysis, complex titration, IR, UV-VIS and fluorescent spectra. The thermal stability, glass temperature and average molecular weight of the copolymer Eu（DBM）2MA-MMA were determined by TG-DTA, DSC and GPC, respectively. The research results show that both of the ternary rare earth complex and the copolymer can emit strong Eu（Ⅲ） fluorescence at 613 nm.
基金supported by the National Natural Science Foundation of China(Nos.21304097,21334007and 21674113)
文摘We use a Monte Carlo method to study the phase and interracial behaviors of A-b-B diblocks in a blend of homopolymers, A and B, which are confined between two asymmetric hard and impenetrable walls. Our results show that, when the interaction strength is weak, the block copolymers are uniformly distributed in the ternary mixtures under considered concentrations. Under strong interaction strength, distribution region of the block copolymers changes from a single smooth interface to a curved interface or multi-layer interface in the ternary mixtures. Furthermore, our findings show that with increasing volume fraction of A-b-B diblock copolymer （φc）, copolymer profiles broaden while φc ≥ 0.4, a lamellar phase is formed and by further increasing φc, more thinner layers are observed. Moreover, the results show that, with the increase of φc, the phase interface first gradually transforms from plane to a curved surface rather than micelle or lamellar phase while with the increase of the interaction between A and B segments （CAB）, the copolymer chains not only get stretched in the direction perpendicular to the interface, but also are oriented. The simulations also reveal that the difference between symmetric and asymmetric copolymers is negligible in statistics if the lengths of two blocks are comparable.
基金the Shenzhen Technology and Innovation Commission(JCYJ20170413173814007,JCYJ20170818113905024)the Hong Kong Research Grants Council(Research Impact Fund R6021-18)(16305915,16322416,606012,16303917)+1 种基金Hong Kong Innovation and Technology Commission(ITCCNERC14SC01,ITS/471/18)the National Natural Science Foundation of China(51573120,51973146,51820105003)。
文摘To achieve high-efficiency polymer solar cells(PSCs),it is not only important to develop high-performance small molecule acceptors(SMAs)but also to find a matching polymer donor to achieve optimal morphology and matching electronic properties.Currently,state-of-the-art SMAs mostly rely on a donor polymer named PM6.However,as the family of SMAs continues to expend,PM6 may not be the perfect polymer donor due to the requirement of energy level matching.In this work,we tune the energy level of PM6 via the strategy of ternary copolymerization.We achieve two donor polymers(named PL-1 and PL-2)with upshifted HOMO(the highest occupied molecular orbital)energy level(compared with PM6),and can thus match with the SMAs with upshifted HOMO energy levels compared with Y6.These two copolymers exhibit slightly higher order of molecular packing and similar charge transport properties,which demonstrate that the method of ternary copolymerization can fine tune the HOMO level of donor polymers,while the morphology and mobility of the blend film remain mostly unaffected.Among them,the best device based on PL-1:Y6 exhibits power conversion efficiencies(PCEs)of 16.37%with lower open circuit voltage(Voc)but higher short circuit current voltage(Jsc)and fill factor(FF)than that of the device based on PM6:Y6.This work provides an effective approach to find polymer matches for the SMAs with upshifted HOMO levels.
