CsPbI_(3)perovskite quantum dots(QDs)have great potential in optoelectronic devices due to their suitable band-gaps,but low photoluminescence quantum yields(PLQYs)and poor phase stability seriously impede their practi...CsPbI_(3)perovskite quantum dots(QDs)have great potential in optoelectronic devices due to their suitable band-gaps,but low photoluminescence quantum yields(PLQYs)and poor phase stability seriously impede their practical application.This paper reports the synthesis of Ce^(3+)-doped CsPbI_(3)QDs by a hot injection method.In the presence of the dopant(Ce^(3+)),the highest PLQY of CsPbI_(3)QDs reached 99%,i.e.,near-unity PLQY,and the photoluminescence(PL)emission of CsPbI_(3)QDs could be well maintained compared to that of the undoped ones.The photoluminescence kinetics of Ce^(3+)-doped CsPbI_(3)QDs was investigated by the ultrafast transient absorption technologies,which exhibited that the Ce^(3+)not only increased the density of excitonic states close to the high energy excitonic states(HES),but also provided more emissive channels.Moreover,the radiative recombination rates calculated by the combination of PL lifetime and PLQY further illustrated the Pb2+vacancies were filled with Ce^(3+)ions so that the PL quenching of the CsPbI_(3)QDs could be effectively prevented.The theoretic analysis uncovered the mechanism of the high PLQY and stable PL emission of the Ce^(3+)-doped CsPbI_(3)QDs.展开更多
Combining high mobility and high-efficiency luminescence in one material is challenging because of their contradictory design principles.Here,under the three-state exciton model,a molecular descriptor O=(|t_(h)+t_(e)|...Combining high mobility and high-efficiency luminescence in one material is challenging because of their contradictory design principles.Here,under the three-state exciton model,a molecular descriptor O=(|t_(h)+t_(e)|−|t_(h)-t_(e)|)∕2Jis proposed to quantitatively design materials with balanced luminescence and mobility in aggregated states,where a large𝑂would promise high crystalline photoluminescence quantum yield(PLQY)with small J(excitonic coupling)and significant t_(h) and t_(e)(hole and electron transfer integrals)would indicate high mobility.Through theoretical calculation and experimental validation,it is found that the asymmetric anthracene derivatives are quite effective in simultaneously achieving high mobility and high PLQY.Following the asymmetric guideline,the newly developed compounds,2-phenyl vinyl anthracene(2-PhVA)and 6-(2-(anthracene-2-yl)vinyl)benzo[b]thiophene(6-BTVA)demonstrate high O values alongside excellent performance:2-PhVA exhibits a PLQY of 81.5%and a maximum hole mobility of 10.0 cm^(2) V^(−1) s^(−1),and 6-BTVA shows a PLQY of 30.9%with a maximum mobility of 9.3 cm^(2) V^(−1) s^(−1).The above results demonstrate the validation of the descriptor and the asymmetric strategy in further developing high-mobility light-emitting aggregated materials.展开更多
Electrogenerated chemiluminescence(ECL)has been extensively used in ultrasensitive electroanalysis because it can be generated electrochemically without using expensive optics and light sources.Visible ECL emission ca...Electrogenerated chemiluminescence(ECL)has been extensively used in ultrasensitive electroanalysis because it can be generated electrochemically without using expensive optics and light sources.Visible ECL emission can be obtained with a reasonable quantum yield and stability.Blue ECL is rare and often suffers from stability and poor quantum efficiency.Blue ECL emission at 473 nm from organometallic halide perovskite nanocrystals(PNCs),CH_(3)NH_(3)PbCl_(1.08)Br_(1.92),is reported here for the first time using tripropylamine(TPrA)as co-reactant.The blue ECL emission peak resembles its photoluminescence peak position.In addition to this blue emission peak,the ECL spectra of CH_(3)NH_(3)PbCl_(1.08)Br_(1.92) PNCs also showed a broad ECL peak at 745 nm.Generation of the second ECL peak at 745 nm from CH_(3)NH_(3)PbCl_(1.08)Br_(1.92) PNCs was can be explained by the existence of surface trap states on as-synthesized PNC due to incomplete surface passivation.Halide anion tunability of ECL emission from CH3NH3PbX3(X:Cl,Br,I)PNCs is also demonstrated.The fluorescence microscopy image of single PNC and stability of selected single PNCs are presented in this with simultaneous acquisition of fluorescence spectra using 405-nm laser excitation.The photoluminescence(PL)decay was described by PL lifetime(τ)of 1.2 ns.The effect of the addition of surfactants(oleic acid and n-octylamine)on the fluorescence intensity and stability of CH_(3)NH_(3)PbCl_(1.08)Br_(1.92) PNCs is also discussed.展开更多
Bright tunable light emission in the short wavelength range from sulfur nanodots was demonstrated with a photoluminescence quantum yield(PLQY)of up to 59.4%.A fission-aggregation mechanism was proposed for the formati...Bright tunable light emission in the short wavelength range from sulfur nanodots was demonstrated with a photoluminescence quantum yield(PLQY)of up to 59.4%.A fission-aggregation mechanism was proposed for the formation of sulfur nanodots with desired performances.This synthetic strategy allowed for simultaneous size control from 3.2 to 5.6 nm,thus tuning the emission color from ultraviolet(UV)to deep blue(342±430 nm),and for the suppression of unwanted nonradiative recombination centers and deep level emission.The luminescence mechanism and quantum confinement effect of the synthesized sulfur nanodots were investigated by optical spectroscopy and theoretical calculations.These results show promise toward the application of sulfur nanodots in UV optoelectronics,biomedical treatments,and sterilization.展开更多
基金This work was finanicially supported by the Key Research and Development Project of Anhui Province of China(No.1704a0902023)the Open Research Fund of State Key Laboratory of Plused Power Laser Technology(No.SKL2019KF09)。
文摘CsPbI_(3)perovskite quantum dots(QDs)have great potential in optoelectronic devices due to their suitable band-gaps,but low photoluminescence quantum yields(PLQYs)and poor phase stability seriously impede their practical application.This paper reports the synthesis of Ce^(3+)-doped CsPbI_(3)QDs by a hot injection method.In the presence of the dopant(Ce^(3+)),the highest PLQY of CsPbI_(3)QDs reached 99%,i.e.,near-unity PLQY,and the photoluminescence(PL)emission of CsPbI_(3)QDs could be well maintained compared to that of the undoped ones.The photoluminescence kinetics of Ce^(3+)-doped CsPbI_(3)QDs was investigated by the ultrafast transient absorption technologies,which exhibited that the Ce^(3+)not only increased the density of excitonic states close to the high energy excitonic states(HES),but also provided more emissive channels.Moreover,the radiative recombination rates calculated by the combination of PL lifetime and PLQY further illustrated the Pb2+vacancies were filled with Ce^(3+)ions so that the PL quenching of the CsPbI_(3)QDs could be effectively prevented.The theoretic analysis uncovered the mechanism of the high PLQY and stable PL emission of the Ce^(3+)-doped CsPbI_(3)QDs.
基金supported by the National Natural Science Foundation of China(T2225028,22475219,12204167,22325305,T2350009,52203210,and 22003030)the Chinese Academy of Sciences(Hundred Talents Plan,Youth Innovation Promotion Association,the Strategic Priority Research Program of Sciences[XDB0520200]and Young Scientists in Basic Research[YSBR-053])the Guangdong Provincial Natural Science Foundation(2024A1515011185).
文摘Combining high mobility and high-efficiency luminescence in one material is challenging because of their contradictory design principles.Here,under the three-state exciton model,a molecular descriptor O=(|t_(h)+t_(e)|−|t_(h)-t_(e)|)∕2Jis proposed to quantitatively design materials with balanced luminescence and mobility in aggregated states,where a large𝑂would promise high crystalline photoluminescence quantum yield(PLQY)with small J(excitonic coupling)and significant t_(h) and t_(e)(hole and electron transfer integrals)would indicate high mobility.Through theoretical calculation and experimental validation,it is found that the asymmetric anthracene derivatives are quite effective in simultaneously achieving high mobility and high PLQY.Following the asymmetric guideline,the newly developed compounds,2-phenyl vinyl anthracene(2-PhVA)and 6-(2-(anthracene-2-yl)vinyl)benzo[b]thiophene(6-BTVA)demonstrate high O values alongside excellent performance:2-PhVA exhibits a PLQY of 81.5%and a maximum hole mobility of 10.0 cm^(2) V^(−1) s^(−1),and 6-BTVA shows a PLQY of 30.9%with a maximum mobility of 9.3 cm^(2) V^(−1) s^(−1).The above results demonstrate the validation of the descriptor and the asymmetric strategy in further developing high-mobility light-emitting aggregated materials.
基金We would like to thank the financial support from the National Science Foundation(NSF award CHE 1508192 and OIA-1539035).
文摘Electrogenerated chemiluminescence(ECL)has been extensively used in ultrasensitive electroanalysis because it can be generated electrochemically without using expensive optics and light sources.Visible ECL emission can be obtained with a reasonable quantum yield and stability.Blue ECL is rare and often suffers from stability and poor quantum efficiency.Blue ECL emission at 473 nm from organometallic halide perovskite nanocrystals(PNCs),CH_(3)NH_(3)PbCl_(1.08)Br_(1.92),is reported here for the first time using tripropylamine(TPrA)as co-reactant.The blue ECL emission peak resembles its photoluminescence peak position.In addition to this blue emission peak,the ECL spectra of CH_(3)NH_(3)PbCl_(1.08)Br_(1.92) PNCs also showed a broad ECL peak at 745 nm.Generation of the second ECL peak at 745 nm from CH_(3)NH_(3)PbCl_(1.08)Br_(1.92) PNCs was can be explained by the existence of surface trap states on as-synthesized PNC due to incomplete surface passivation.Halide anion tunability of ECL emission from CH3NH3PbX3(X:Cl,Br,I)PNCs is also demonstrated.The fluorescence microscopy image of single PNC and stability of selected single PNCs are presented in this with simultaneous acquisition of fluorescence spectra using 405-nm laser excitation.The photoluminescence(PL)decay was described by PL lifetime(τ)of 1.2 ns.The effect of the addition of surfactants(oleic acid and n-octylamine)on the fluorescence intensity and stability of CH_(3)NH_(3)PbCl_(1.08)Br_(1.92) PNCs is also discussed.
基金financially supported by A*STAR(AME-IRG-A20E5c0083)the National Natural Science Foundation of China(52006005)。
文摘Bright tunable light emission in the short wavelength range from sulfur nanodots was demonstrated with a photoluminescence quantum yield(PLQY)of up to 59.4%.A fission-aggregation mechanism was proposed for the formation of sulfur nanodots with desired performances.This synthetic strategy allowed for simultaneous size control from 3.2 to 5.6 nm,thus tuning the emission color from ultraviolet(UV)to deep blue(342±430 nm),and for the suppression of unwanted nonradiative recombination centers and deep level emission.The luminescence mechanism and quantum confinement effect of the synthesized sulfur nanodots were investigated by optical spectroscopy and theoretical calculations.These results show promise toward the application of sulfur nanodots in UV optoelectronics,biomedical treatments,and sterilization.
