Jiajie Zeng - Academia.edu (original) (raw)

Papers by Jiajie Zeng

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Thermally Activated Delayed Fluorescence Organic Light-Emitting Diodes (TADF-OLEDs), 2022

CCS Chemistry, 2021

Severe efficiency instability is still a huge challenge for most organic light-emitting diodes (O... more Severe efficiency instability is still a huge challenge for most organic light-emitting diodes (OLEDs) based on thermally activated delayed fluorescence (TADF) molecules, frustrating their industrial application. To address this issue, herein we report two robust luminogens, 3,6-bis(9,9-dimethylacridin-10-yl)-xanthen-9-one (BDMAC-XT) and 3,6-bis(9,9-diphenylacridin-10)-yl)-xanthen-9-one (BDPAC-XT), comprised of electron-accepting 3,6-dibromoxanthen-9-one and electron-donating 9,9-dimethyl-9,10-dihydroacridine and 9,9-diphenyl-9,10-dihydroacridine. BDMAC-XT and BDPAC-XT show interesting aggregationenhanced delayed fluorescence characteristics with excellent photoluminescence quantum yields of 96% and 94% in neat films. Nondoped OLEDs based on BDMAC-XT emit intense green light with high external quantum yields (η ext ; 21%) and hardly any efficiency roll-off (∼0%) at 1000 cd m −2. High-performance sky-blue nondoped OLEDs are achieved using BDPAC-XT as emitter, providing impressive η ext values (21%). Both luminogens can also function efficiently as dopants in doped OLEDs, furnishing excellent η ext values (27%) and very small efficiency roll-offs down to 3.7% at 1000 cd m −2. Moreover, they can perform as excellent hosts for orange and red phosphorescent OLEDs, leading to η ext values of up to 26% and 20%, respectively. These results demonstrate that they are promising versatile functional materials for high-efficiency nondoped and doped OLEDs with superb efficiency stability.

Journal of Materials Chemistry C, 2021

A comparative study on the impacts of through-space charge transfer and through-bond charge trans... more A comparative study on the impacts of through-space charge transfer and through-bond charge transfer on the photoluminescence and electroluminescence properties of the delayed fluorescence molecules is conducted.

Advanced Optical Materials, 2021

Advanced Optical Materials, 2021

Organic blue luminescent materials play a vital role in the fabrication of full‐color displays an... more Organic blue luminescent materials play a vital role in the fabrication of full‐color displays and white lighting devices, but high‐efficiency blue emitters that meet commercial demands are still quite insufficient. Herein, the authors wish to report the design and synthesis of four bipolar deep‐blue luminogens consisting of an anthracene core and various functional groups. Their photophysical properties, electronic structures, electrochemical behavior, thermal stability, carrier transport ability, and electroluminescence performance are systematically studied. The nondoped organic light‐emitting diode (OLED) based on DPAC‐TAn‐BI radiates stable deep‐blue light [Commission Internationale de l'Eclairage (CIEx,y) = 0.15, 0.15] with a high external quantum efficiency (ηext) of 5.81%. Moreover, efficient two‐color hybrid warm white OLEDs are achieved using DPAC‐TAn‐BI neat film as a blue‐emitting layer, providing an excellent ηext of 27.6%, a small efficiency roll‐off of 2.9% at 1000 cd m−2, and ultra‐stable emission spectra with tiny CIEx,y variation of (0.01, 0.01) from 100 to 10 000 cd m−2. These results demonstrate that the deep‐blue luminogens are strong candidates for applications in blue and white OLEDs.

Journal of Materials Chemistry C, 2020

The integration of bipolar carrier transport materials with an aggregation-induced delayed fluore... more The integration of bipolar carrier transport materials with an aggregation-induced delayed fluorescence unit generates robust luminescent materials, which lead to efficient nondoped OLEDs with high efficiency stability.

Advanced Functional Materials, 2020

Increasing exciton utilization and reducing exciton annihilation are crucial to achieve high perf... more Increasing exciton utilization and reducing exciton annihilation are crucial to achieve high performance of organic light-emitting diodes (OLEDs), which greatly depend on molecular engineering of emitters and hosts. A novel luminogen (SBF-BP-DMAC) is synthesized and characterized. Its crystal and electronic structures, thermal stability, electrochemical behavior, carrier transport, photoluminescence, and electroluminescence are investigated. SBF-BP-DMAC exhibits enhanced photoluminescence and promotes delayed fluorescence in solid state and bipolar carrier transport ability, and thus holds multifunctionality of emitter and host for OLEDs. Using SBF-BP-DMAC as an emitter, the nondoped OLEDs exhibit maximum electroluminescence (EL) efficiencies of 67.2 cd A −1 , 65.9 lm W −1 , and 20.1%, and the doped OLEDs provide maximum EL efficiencies of 79.1 cd A −1 , 70.7 lm W −1 , and 24.5%. A representative orange phosphor, Ir(tptpy) 2 acac, is doped into SBF-BP-DMAC for OLED fabrication, giving rise to superior EL efficiencies of 88.0 cd A −1 , 108.0 lm W −1 , and 26.8% for orange phosphorescent OLEDs, and forwardviewing EL efficiencies of 69.3 cd A −1 , 45.8 lm W −1 , and 21.0% for two-color hybrid warm-white OLEDs. All of these OLEDs can retain high EL efficiencies at high luminance, with very small efficiency roll-offs. The outstanding EL performance demonstrates the great potentials of SBF-BP-DMAC in practical display and lighting devices. luminous efficiencies and efficient exciton utilization approaching 100%. [2] However, commercial phosphors depend on rare metal elements such as iridium and platinum, and thus are usually expensive. What is more, high doping concentrations (5-20 wt%) of phosphors were recently reported to optimize the device performance, leading to a high manufacturing cost. [3] As promising alternatives, Adachi and co-workers developed purely organic luminescent materials with thermally activated delayed fluorescence (TADF), which can fully utilize the electrogenerated excitons in OLEDs and thus afford excellent external quantum efficiencies (ƞ ext) of >20% via reverse intersystem crossing (RISC) process based on small singlet-triplet energy gaps (ΔE ST ≤ 0.3 eV) of the molecules. [4] However, on account of the long triplet lifetimes, most phosphors and TADF emitters suffer from negative nonradiative processes in OLEDs, such as aggregation and concentration caused quenching, [5] triplet-triplet annihilation (TTA), [6] singlet-triplet annihilation (STA), [7] and so on, [8] which greatly limits their practical applications. To address the issue, robust luminogens that can alleviate emission quenching and exciton annihilation are extremely desired. According to the previous works, reducing the intermolecular interactions (e.g., π-π interactions) has been evidenced to be an effective strategy to develop efficient luminescent materials with high photoluminescence quantum yields (Φ F s) in neat films and prominent delayed fluorescence. [9] By this way, the emitters are usually insensitive to concentrations, which means they can be utilized in nondoped OLEDs as well as doped OLEDs with various doping concentrations. [10] For example, in order to suppress intermolecular annihilations, the bulky 3,6-di-tert-butyl-9H-carbazol-9-yl (tCz) group was introduced in t2tCz2CzBn, a TADF emitter. Nondoped and doped blue OLEDs were fabricated based on t2tCz2CzBn, affording high ƞ ext values of 21.6% and 23.8%, respectively. [11] Similarly, the tCz group was used to block intermolecular electron exchanges in another blue TADF emitter, DPAc-DtCzBN, displaying ƞ ext values of 20.0% and 23.1% for nondoped and doped OLEDs, respectively. [12] However, the efficiency roll-offs in these systems were serious, probably due to the imbalanced charges in the OLEDs.

Journal of Materials Chemistry C, 2019

Decorating a conventional mCP host with a tetraphenylpyrazine moiety generates a new AIE-active h... more Decorating a conventional mCP host with a tetraphenylpyrazine moiety generates a new AIE-active host, from which better device performance was realized.

ACS Applied Materials & Interfaces, 2019

Host materials are indispensable for the fabrication of OLEDs with phosphorescent emitters, but h... more Host materials are indispensable for the fabrication of OLEDs with phosphorescent emitters, but high-quality host materials that can efficiently and simultaneously function in blue, green and red phosphorescent OLEDs (PHOLEDs) are much rare. In this work, four bipolar materials are developed using carbazole and 9,9-dimethyl-9,10-dihydroacridine as hole-transporting groups, pyridine as electron-transporting group, and biphenyl and m-methylbiphenyl as π-spacers. The crystal and electronic structures indicate that these materials have highly twisted conformations, which endow them with aggregation-induced emission features, intramolecular charge transfer processes, wide energy bandgaps and high triplet energies. The carrier transport ability and energy transfer property analyses show that these materials are able to achieve balanced hole and electron transports, and can serve as bipolar host materials for PHOLEDs. A series of monochromatic PHOLEDs with different phosphorescent dopants, including blue emissive FIrpic, green emissive Ir(ppy) 2 (acac) and red emissive Ir(piq) 2 (acac) are fabricated by employing these four host materials. The green PHOLEDs can provide an impressive luminance of up to 230200 cd m −2. Based on an identical host material, excellent external quantum efficiencies as high as 25.12%, 24.73% and 19.71%, as well as minor efficiency roll-off, are attained for blue, green and red PHOLEDs, respectively, clearly demonstrating the promising applications as universal bipolar host materials in PHOLEDs with monochromatic light and white light.

Journal of Materials Chemistry C, 2019

Combining HLCT and AIE characteristics, six phenanthroimidazole derivatives were designed with di... more Combining HLCT and AIE characteristics, six phenanthroimidazole derivatives were designed with different patterns for high-efficiency non-doped OLEDs.

Chinese Chemical Letters, 2018

New aggregation-induced emission molecules of carbazole-substituted siloles are prepared, based o... more New aggregation-induced emission molecules of carbazole-substituted siloles are prepared, based on which efficient non-doped OLEDs are fabricated, offering high external quantum efficiencies of up to 5.63%.

Journal of Materials Chemistry C, 2018

New robust n-type light emitters are developed from AIE-active silole derivatives, enabling the O... more New robust n-type light emitters are developed from AIE-active silole derivatives, enabling the OLEDs to operate efficiently in a simplified configuration.

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Thermally Activated Delayed Fluorescence Organic Light-Emitting Diodes (TADF-OLEDs), 2022

CCS Chemistry, 2021

Severe efficiency instability is still a huge challenge for most organic light-emitting diodes (O... more Severe efficiency instability is still a huge challenge for most organic light-emitting diodes (OLEDs) based on thermally activated delayed fluorescence (TADF) molecules, frustrating their industrial application. To address this issue, herein we report two robust luminogens, 3,6-bis(9,9-dimethylacridin-10-yl)-xanthen-9-one (BDMAC-XT) and 3,6-bis(9,9-diphenylacridin-10)-yl)-xanthen-9-one (BDPAC-XT), comprised of electron-accepting 3,6-dibromoxanthen-9-one and electron-donating 9,9-dimethyl-9,10-dihydroacridine and 9,9-diphenyl-9,10-dihydroacridine. BDMAC-XT and BDPAC-XT show interesting aggregationenhanced delayed fluorescence characteristics with excellent photoluminescence quantum yields of 96% and 94% in neat films. Nondoped OLEDs based on BDMAC-XT emit intense green light with high external quantum yields (η ext ; 21%) and hardly any efficiency roll-off (∼0%) at 1000 cd m −2. High-performance sky-blue nondoped OLEDs are achieved using BDPAC-XT as emitter, providing impressive η ext values (21%). Both luminogens can also function efficiently as dopants in doped OLEDs, furnishing excellent η ext values (27%) and very small efficiency roll-offs down to 3.7% at 1000 cd m −2. Moreover, they can perform as excellent hosts for orange and red phosphorescent OLEDs, leading to η ext values of up to 26% and 20%, respectively. These results demonstrate that they are promising versatile functional materials for high-efficiency nondoped and doped OLEDs with superb efficiency stability.

Journal of Materials Chemistry C, 2021

A comparative study on the impacts of through-space charge transfer and through-bond charge trans... more A comparative study on the impacts of through-space charge transfer and through-bond charge transfer on the photoluminescence and electroluminescence properties of the delayed fluorescence molecules is conducted.

Advanced Optical Materials, 2021

Advanced Optical Materials, 2021

Organic blue luminescent materials play a vital role in the fabrication of full‐color displays an... more Organic blue luminescent materials play a vital role in the fabrication of full‐color displays and white lighting devices, but high‐efficiency blue emitters that meet commercial demands are still quite insufficient. Herein, the authors wish to report the design and synthesis of four bipolar deep‐blue luminogens consisting of an anthracene core and various functional groups. Their photophysical properties, electronic structures, electrochemical behavior, thermal stability, carrier transport ability, and electroluminescence performance are systematically studied. The nondoped organic light‐emitting diode (OLED) based on DPAC‐TAn‐BI radiates stable deep‐blue light [Commission Internationale de l'Eclairage (CIEx,y) = 0.15, 0.15] with a high external quantum efficiency (ηext) of 5.81%. Moreover, efficient two‐color hybrid warm white OLEDs are achieved using DPAC‐TAn‐BI neat film as a blue‐emitting layer, providing an excellent ηext of 27.6%, a small efficiency roll‐off of 2.9% at 1000 cd m−2, and ultra‐stable emission spectra with tiny CIEx,y variation of (0.01, 0.01) from 100 to 10 000 cd m−2. These results demonstrate that the deep‐blue luminogens are strong candidates for applications in blue and white OLEDs.

Journal of Materials Chemistry C, 2020

The integration of bipolar carrier transport materials with an aggregation-induced delayed fluore... more The integration of bipolar carrier transport materials with an aggregation-induced delayed fluorescence unit generates robust luminescent materials, which lead to efficient nondoped OLEDs with high efficiency stability.

Advanced Functional Materials, 2020

Increasing exciton utilization and reducing exciton annihilation are crucial to achieve high perf... more Increasing exciton utilization and reducing exciton annihilation are crucial to achieve high performance of organic light-emitting diodes (OLEDs), which greatly depend on molecular engineering of emitters and hosts. A novel luminogen (SBF-BP-DMAC) is synthesized and characterized. Its crystal and electronic structures, thermal stability, electrochemical behavior, carrier transport, photoluminescence, and electroluminescence are investigated. SBF-BP-DMAC exhibits enhanced photoluminescence and promotes delayed fluorescence in solid state and bipolar carrier transport ability, and thus holds multifunctionality of emitter and host for OLEDs. Using SBF-BP-DMAC as an emitter, the nondoped OLEDs exhibit maximum electroluminescence (EL) efficiencies of 67.2 cd A −1 , 65.9 lm W −1 , and 20.1%, and the doped OLEDs provide maximum EL efficiencies of 79.1 cd A −1 , 70.7 lm W −1 , and 24.5%. A representative orange phosphor, Ir(tptpy) 2 acac, is doped into SBF-BP-DMAC for OLED fabrication, giving rise to superior EL efficiencies of 88.0 cd A −1 , 108.0 lm W −1 , and 26.8% for orange phosphorescent OLEDs, and forwardviewing EL efficiencies of 69.3 cd A −1 , 45.8 lm W −1 , and 21.0% for two-color hybrid warm-white OLEDs. All of these OLEDs can retain high EL efficiencies at high luminance, with very small efficiency roll-offs. The outstanding EL performance demonstrates the great potentials of SBF-BP-DMAC in practical display and lighting devices. luminous efficiencies and efficient exciton utilization approaching 100%. [2] However, commercial phosphors depend on rare metal elements such as iridium and platinum, and thus are usually expensive. What is more, high doping concentrations (5-20 wt%) of phosphors were recently reported to optimize the device performance, leading to a high manufacturing cost. [3] As promising alternatives, Adachi and co-workers developed purely organic luminescent materials with thermally activated delayed fluorescence (TADF), which can fully utilize the electrogenerated excitons in OLEDs and thus afford excellent external quantum efficiencies (ƞ ext) of >20% via reverse intersystem crossing (RISC) process based on small singlet-triplet energy gaps (ΔE ST ≤ 0.3 eV) of the molecules. [4] However, on account of the long triplet lifetimes, most phosphors and TADF emitters suffer from negative nonradiative processes in OLEDs, such as aggregation and concentration caused quenching, [5] triplet-triplet annihilation (TTA), [6] singlet-triplet annihilation (STA), [7] and so on, [8] which greatly limits their practical applications. To address the issue, robust luminogens that can alleviate emission quenching and exciton annihilation are extremely desired. According to the previous works, reducing the intermolecular interactions (e.g., π-π interactions) has been evidenced to be an effective strategy to develop efficient luminescent materials with high photoluminescence quantum yields (Φ F s) in neat films and prominent delayed fluorescence. [9] By this way, the emitters are usually insensitive to concentrations, which means they can be utilized in nondoped OLEDs as well as doped OLEDs with various doping concentrations. [10] For example, in order to suppress intermolecular annihilations, the bulky 3,6-di-tert-butyl-9H-carbazol-9-yl (tCz) group was introduced in t2tCz2CzBn, a TADF emitter. Nondoped and doped blue OLEDs were fabricated based on t2tCz2CzBn, affording high ƞ ext values of 21.6% and 23.8%, respectively. [11] Similarly, the tCz group was used to block intermolecular electron exchanges in another blue TADF emitter, DPAc-DtCzBN, displaying ƞ ext values of 20.0% and 23.1% for nondoped and doped OLEDs, respectively. [12] However, the efficiency roll-offs in these systems were serious, probably due to the imbalanced charges in the OLEDs.

Journal of Materials Chemistry C, 2019

Decorating a conventional mCP host with a tetraphenylpyrazine moiety generates a new AIE-active h... more Decorating a conventional mCP host with a tetraphenylpyrazine moiety generates a new AIE-active host, from which better device performance was realized.

ACS Applied Materials & Interfaces, 2019

Host materials are indispensable for the fabrication of OLEDs with phosphorescent emitters, but h... more Host materials are indispensable for the fabrication of OLEDs with phosphorescent emitters, but high-quality host materials that can efficiently and simultaneously function in blue, green and red phosphorescent OLEDs (PHOLEDs) are much rare. In this work, four bipolar materials are developed using carbazole and 9,9-dimethyl-9,10-dihydroacridine as hole-transporting groups, pyridine as electron-transporting group, and biphenyl and m-methylbiphenyl as π-spacers. The crystal and electronic structures indicate that these materials have highly twisted conformations, which endow them with aggregation-induced emission features, intramolecular charge transfer processes, wide energy bandgaps and high triplet energies. The carrier transport ability and energy transfer property analyses show that these materials are able to achieve balanced hole and electron transports, and can serve as bipolar host materials for PHOLEDs. A series of monochromatic PHOLEDs with different phosphorescent dopants, including blue emissive FIrpic, green emissive Ir(ppy) 2 (acac) and red emissive Ir(piq) 2 (acac) are fabricated by employing these four host materials. The green PHOLEDs can provide an impressive luminance of up to 230200 cd m −2. Based on an identical host material, excellent external quantum efficiencies as high as 25.12%, 24.73% and 19.71%, as well as minor efficiency roll-off, are attained for blue, green and red PHOLEDs, respectively, clearly demonstrating the promising applications as universal bipolar host materials in PHOLEDs with monochromatic light and white light.

Journal of Materials Chemistry C, 2019

Combining HLCT and AIE characteristics, six phenanthroimidazole derivatives were designed with di... more Combining HLCT and AIE characteristics, six phenanthroimidazole derivatives were designed with different patterns for high-efficiency non-doped OLEDs.

Chinese Chemical Letters, 2018

New aggregation-induced emission molecules of carbazole-substituted siloles are prepared, based o... more New aggregation-induced emission molecules of carbazole-substituted siloles are prepared, based on which efficient non-doped OLEDs are fabricated, offering high external quantum efficiencies of up to 5.63%.

Journal of Materials Chemistry C, 2018

New robust n-type light emitters are developed from AIE-active silole derivatives, enabling the O... more New robust n-type light emitters are developed from AIE-active silole derivatives, enabling the OLEDs to operate efficiently in a simplified configuration.