Direct photopatterning is a powerful strategy for patterning colloidal quantum dots(QDs)for their integration in various electronic and optoelectronic devices.However,ultraviolet(UV)exposure required for QD patterning...Direct photopatterning is a powerful strategy for patterning colloidal quantum dots(QDs)for their integration in various electronic and optoelectronic devices.However,ultraviolet(UV)exposure required for QD patterning,especially those with short wavelength(e.g.,deep UV light),can degrade the photo-,and electroluminescence,and other properties of patterned QDs.Here we develop a photosensitizer-assisted approach for direct photopatterning of QDs with h-line(centered at 405 nm)UV light and better preservation of their luminescent properties.This approach uses a photosensitizer that can absorb the h-line UV light and transfer the energy to activate bisazide-based crosslinkers via Dexter energy transfer.Uniform,high-resolution(smallest feature size,2μm),and full-color patterns of red,green,and blue QD layers can be achieved.The patterned QD layers maintain up to~90%of their original photoluminescent quantum yields,comparing favorably with those(<60%)of QDs patterned without photosensitizers.We further extended the strategy to the direct three-dimensional(3D)printing of QDs.This photosensitizerassisted approach offers a new way for direct two-dimensional(2D)photopatterning and 3D printing of colloidal QDs,with implications in building high-performance QD optoelectronic devices.展开更多
Quantum dot light-emitting diodes(QLEDs)are a class of high-performance solution-processed electroluminescent(EL)devices highly attractive for next-generation display applications.Despite the encouraging advances in t...Quantum dot light-emitting diodes(QLEDs)are a class of high-performance solution-processed electroluminescent(EL)devices highly attractive for next-generation display applications.Despite the encouraging advances in the mechanism investigation,material chemistry,and device engineering of QLEDs,the lack of standard protocols for the characterization of QLEDs may cause inaccurate measurements of device parameters and invalid comparison of different devices.Here,we report a comprehensive study on the characterizations of QLEDs using various methods.We show that the emission non-uniformity across the active area,nonLambertian angular distributions of EL intensity,and discrepancies in the adopted spectral luminous efficiency functions could introduce significant errors in the device efficiency.Larger errors in the operational-lifetime measurements may arise from the inaccurate determination of the initial luminance and inconsistent methods for analyzing the luminance-decay curves.Finally,we suggest a set of recommended practices and a checklist for device characterizations,aiming to help the researchers in the QLED field to achieve accurate and reliable measurements.展开更多
The shelf-stability issue,originating from the ZnO-induced positive aging effect,poses a significant challenge to industrializing the display technology based on solution-processed quantum-dot light-emitting diodes(QL...The shelf-stability issue,originating from the ZnO-induced positive aging effect,poses a significant challenge to industrializing the display technology based on solution-processed quantum-dot light-emitting diodes(QLEDs).Currently,none of the proposed solutions can simultaneously inhibit exciton quenching caused by the ZnO-based electron-transporting layer(ETL)and retain other advantages of ZnO.Here in this work,we propose a bilayer design of ETL in which a buffer layer assembled of SnO_(2) nanoparticles(NPs)suppresses the QD-ETL exciton quenching and tunes charge balance while ZnO NPs provide high electron conductivity.As a result,the bottom-emitting QLED combining capped ZnO and SnO_(2) buffer exhibit a maximum luminance over 100,000 cd m^(−2) and a T95 operational lifetime averaging 6200 h at 1000 cd m^(−2) on the premise of entirely inhibiting positive aging.展开更多
基金supported by National Key Research and Development Program of China(No.2022YFB3602805)(H.Z.)the National Natural Science Foundation of China(No.22274087)(H.Z.)Tsinghua University Dushi Program(H.Z.).
文摘Direct photopatterning is a powerful strategy for patterning colloidal quantum dots(QDs)for their integration in various electronic and optoelectronic devices.However,ultraviolet(UV)exposure required for QD patterning,especially those with short wavelength(e.g.,deep UV light),can degrade the photo-,and electroluminescence,and other properties of patterned QDs.Here we develop a photosensitizer-assisted approach for direct photopatterning of QDs with h-line(centered at 405 nm)UV light and better preservation of their luminescent properties.This approach uses a photosensitizer that can absorb the h-line UV light and transfer the energy to activate bisazide-based crosslinkers via Dexter energy transfer.Uniform,high-resolution(smallest feature size,2μm),and full-color patterns of red,green,and blue QD layers can be achieved.The patterned QD layers maintain up to~90%of their original photoluminescent quantum yields,comparing favorably with those(<60%)of QDs patterned without photosensitizers.We further extended the strategy to the direct three-dimensional(3D)printing of QDs.This photosensitizerassisted approach offers a new way for direct two-dimensional(2D)photopatterning and 3D printing of colloidal QDs,with implications in building high-performance QD optoelectronic devices.
基金supported by National Natural Science Foundation of China (21975220,91833303,21922305,21873080,21703202,62122034,and 61875082)Key Research and Development Project of Zhejiang Province (2020C01001)+1 种基金National Key Research and Development Program of China (2021YFB3601700)China Postdoctoral Science Foundation (2021M702800).
文摘Quantum dot light-emitting diodes(QLEDs)are a class of high-performance solution-processed electroluminescent(EL)devices highly attractive for next-generation display applications.Despite the encouraging advances in the mechanism investigation,material chemistry,and device engineering of QLEDs,the lack of standard protocols for the characterization of QLEDs may cause inaccurate measurements of device parameters and invalid comparison of different devices.Here,we report a comprehensive study on the characterizations of QLEDs using various methods.We show that the emission non-uniformity across the active area,nonLambertian angular distributions of EL intensity,and discrepancies in the adopted spectral luminous efficiency functions could introduce significant errors in the device efficiency.Larger errors in the operational-lifetime measurements may arise from the inaccurate determination of the initial luminance and inconsistent methods for analyzing the luminance-decay curves.Finally,we suggest a set of recommended practices and a checklist for device characterizations,aiming to help the researchers in the QLED field to achieve accurate and reliable measurements.
基金supported by the National Key Research and Development Program of China (Grant 2021YFB3601700)the National Natural Science Foundation of China (Grant 62275183)+4 种基金the Natural Science Foundation of the Jiangsu Higher Education Institutions of China (19KJA550001)Key Lab of Modern Optical Technologies of Education Ministry of ChinaKey Lab of Advanced Optical Manufacturing Technologies of Jiangsu ProvincePriority Academic Program Development (PAPD)of Jiangsu Higher Education InstitutionsJiangsu Shuangchuang Plan.
文摘The shelf-stability issue,originating from the ZnO-induced positive aging effect,poses a significant challenge to industrializing the display technology based on solution-processed quantum-dot light-emitting diodes(QLEDs).Currently,none of the proposed solutions can simultaneously inhibit exciton quenching caused by the ZnO-based electron-transporting layer(ETL)and retain other advantages of ZnO.Here in this work,we propose a bilayer design of ETL in which a buffer layer assembled of SnO_(2) nanoparticles(NPs)suppresses the QD-ETL exciton quenching and tunes charge balance while ZnO NPs provide high electron conductivity.As a result,the bottom-emitting QLED combining capped ZnO and SnO_(2) buffer exhibit a maximum luminance over 100,000 cd m^(−2) and a T95 operational lifetime averaging 6200 h at 1000 cd m^(−2) on the premise of entirely inhibiting positive aging.
