An optimized compound 9-(9,9-dimethylacridin-10(9 H)-yl)-6 H-benzo[c]ch-romen-6-one(MAB)was designed and synthesized based on our previously reported TADF emitter 6-(9,9-dimethylacridin-10(9 H)-yl)-3-methyl-1 H-isochr...An optimized compound 9-(9,9-dimethylacridin-10(9 H)-yl)-6 H-benzo[c]ch-romen-6-one(MAB)was designed and synthesized based on our previously reported TADF emitter 6-(9,9-dimethylacridin-10(9 H)-yl)-3-methyl-1 H-isochromen-1-one(MAC)to further improve the performance of thermally activated delayed fluorescence(TADF)emitters.With the additional phenyl in coumarin-contained plane,MAB possesses an extended distribution of the lowest unoccupied molecular orbitals(LUMO),and thus realizes reduced electron exchange between the frontier molecular orbitals and a stretched molecular dipole moment compared with MAC.MAB based organic light-emitting diode(OLED)exhibits a remarkable maximum external quantum efficiency(EQE)of 21.7%,which is much better than the maximum EQE of MAC-based OLED with a value of 12.8%.Our work proves that extending the distribution of LUMO is a simple but effective method to improve the efficiency of TADF emitter.展开更多
The open-circuit voltage （Voc） of classical photovoltaic polymers, such as P3HT and PTB7-Th, are always restricted when combining with fullerene derivatives, due to the difficulty of modulating the energy levels of ...The open-circuit voltage （Voc） of classical photovoltaic polymers, such as P3HT and PTB7-Th, are always restricted when combining with fullerene derivatives, due to the difficulty of modulating the energy levels of fullerene derivatives. Thus, design of new non-fullerene small molecule acceptor （NFSMA） is very significant to match with these mature polymer donors and improve the Voc and power conversion efficiency （PCE）. Here, a new benzotriazole （BTA）-based NFSMA, BTA7 was synthesized by adopting A2----A1--D--A1--A2 type molecular backbone. By using a strong electron-accepting unit of malononitrile （M） as terminal segment A2, BTA7 demonstrates strong crystallinity, red-shifted absorption spectrum and down-shifted lowest unoccupied molecular orbital （LUMO） energy levels in comparison with BTA1 and BTA2. Organic solar cells （OSCs） based on PTB7-Th：BTA7 realized a high Voc of 1.05 V with a moderate PCE of 4.60%. The energy loss （Eloss = Eg - eVoc） of 0.53 eV is lower than the experiential minimum value of 0.6 eV, which indicates PTB7-Th still has large potential to improve the Voc and photovoltaic performance after the development of novel electron acceptors.展开更多
基金supported by the National Natural Science Foundation of China(51773029,51533005 and 51373190)the National Key Research&Development Program of China(2016YFB0401002)+1 种基金Collaborative Innovation Center of Suzhou Nano Science&Technology,the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)the 111 Project and Qing Lan Project,China
文摘An optimized compound 9-(9,9-dimethylacridin-10(9 H)-yl)-6 H-benzo[c]ch-romen-6-one(MAB)was designed and synthesized based on our previously reported TADF emitter 6-(9,9-dimethylacridin-10(9 H)-yl)-3-methyl-1 H-isochromen-1-one(MAC)to further improve the performance of thermally activated delayed fluorescence(TADF)emitters.With the additional phenyl in coumarin-contained plane,MAB possesses an extended distribution of the lowest unoccupied molecular orbitals(LUMO),and thus realizes reduced electron exchange between the frontier molecular orbitals and a stretched molecular dipole moment compared with MAC.MAB based organic light-emitting diode(OLED)exhibits a remarkable maximum external quantum efficiency(EQE)of 21.7%,which is much better than the maximum EQE of MAC-based OLED with a value of 12.8%.Our work proves that extending the distribution of LUMO is a simple but effective method to improve the efficiency of TADF emitter.
基金supported by the National Key Research and Development Program of China (2017YFA0206600)the Key Research Program of Frontier Sciences, Chinese Academy of Sciences (QYZDB-SSW-SLH033)+1 种基金the National Natural Science Foundation of China (51673048, 51473040 and 21602040)the Natural Science Foundation of Beijing (2162045)
文摘The open-circuit voltage （Voc） of classical photovoltaic polymers, such as P3HT and PTB7-Th, are always restricted when combining with fullerene derivatives, due to the difficulty of modulating the energy levels of fullerene derivatives. Thus, design of new non-fullerene small molecule acceptor （NFSMA） is very significant to match with these mature polymer donors and improve the Voc and power conversion efficiency （PCE）. Here, a new benzotriazole （BTA）-based NFSMA, BTA7 was synthesized by adopting A2----A1--D--A1--A2 type molecular backbone. By using a strong electron-accepting unit of malononitrile （M） as terminal segment A2, BTA7 demonstrates strong crystallinity, red-shifted absorption spectrum and down-shifted lowest unoccupied molecular orbital （LUMO） energy levels in comparison with BTA1 and BTA2. Organic solar cells （OSCs） based on PTB7-Th：BTA7 realized a high Voc of 1.05 V with a moderate PCE of 4.60%. The energy loss （Eloss = Eg - eVoc） of 0.53 eV is lower than the experiential minimum value of 0.6 eV, which indicates PTB7-Th still has large potential to improve the Voc and photovoltaic performance after the development of novel electron acceptors.
