In this study, a low complexity frame-rate up conversion method using compressed domain information for H.264 decoder is proposed. In the proposed scheme, the motion vectors （MVs） are estimated using constant accele...In this study, a low complexity frame-rate up conversion method using compressed domain information for H.264 decoder is proposed. In the proposed scheme, the motion vectors （MVs） are estimated using constant acceleration motion model, and the MVs regarded as no credibility are corrected, and the interpolation method is applied on the basis of the macroblock （MB） coded types. Applied to the H.264 decoder, the proposed method provides high quality interpolation frames and an obvious decrease of the block artifacts.展开更多
High efficiency frequency up conversion in trivalent erbium ion doped new fluoride glass matrix (ZnF 2 AlF 3 PbF 2 LiF) was investigated. Under 950 nm laser diode excitation, the glasses gave very intense gre...High efficiency frequency up conversion in trivalent erbium ion doped new fluoride glass matrix (ZnF 2 AlF 3 PbF 2 LiF) was investigated. Under 950 nm laser diode excitation, the glasses gave very intense green, weak red and violet emissions. The up conversion mechanism is discussed. In addition, the infrared transmittance spectrum, the Raman spectrum and the lifetime of the trivalent erbium states in the samples were measured. The results illustrate the large potential of these new glasses for photonic applications.展开更多
Current optical storage technologies utilizing phosphor media face challenges in achieving rapid and precise data recording with visible or infrared light,primarily due to the constraints of traditional charging techn...Current optical storage technologies utilizing phosphor media face challenges in achieving rapid and precise data recording with visible or infrared light,primarily due to the constraints of traditional charging techniques.Here,we introduce a cutting-edge method termed up-conversion charging(UCC)to address these challenges,enabling rapid and high-resolution data storage in phosphors.Our study focuses on the unique two-step ionization and non-linear charging characteristics of UCC in storage phosphors,specifically in a gallate composition Gd3Ga5O12:Cr3+.Remarkably,this technique enables data writing with high solution,requiring only 0.01 s of exposure per bit when utilizing a portable laser engraver equipped with visible-emitting diode lasers.The present strategy not only enhances recording efficiency but also ensures long-term data retention and superior rewritability.Moreover,we illustrate the versatility of UCC storage across various material systems through thermally-and optically-stimulated luminescence.Our outcomes highlight the transformative potential of the UCC method in advancing optical storage applications,offering significant improvements in the development of information storage solutions.展开更多
This paper reports the preparation of yttrium oxide(Y_(2)O_(3))doped with various concentrations of Er^(3+)using high temperature synthesis method.Photoluminescence(PL)emission spectra of the samples were recorded at ...This paper reports the preparation of yttrium oxide(Y_(2)O_(3))doped with various concentrations of Er^(3+)using high temperature synthesis method.Photoluminescence(PL)emission spectra of the samples were recorded at an excitation of 980 nm laser source.Two prominent peaks centered at 484 nm and 574 nm were found and attributed to the^(2)P3/2→^(4)I_(11/2)and^(4)S_(3/2)→^(4)I_(15/2),respectively.The sample with 2.5 mol%of Er^(3+)provided the optimum intensity in emission spectra.The sample with optimum PL emission was investigated for its thermoluminescence(TL)glow curve exhibited the second order kinetics.The peak TL intensity was found around 236°C,i.e.,towards high temperature which supports the fact of formation of deeper traps.Therefore,the material taken may be regarded as a good candidate for light emitting diode(LED)applications.展开更多
CONSPECTUS:Efficient photovoltaics(PV)require capturing and converting solar energy across a broad range of energy.Losses due to thermalization and sub-bandgap photons place,however,significant boundaries on the perfo...CONSPECTUS:Efficient photovoltaics(PV)require capturing and converting solar energy across a broad range of energy.Losses due to thermalization and sub-bandgap photons place,however,significant boundaries on the performance of solar cells.For conventional singlejunction cells,the theoretical maximum power conversion efficiency is capped at 33%,a constraint known as the detailed balance limit.Realizing the full potential of PVs requires developing novel strategies to overcome this fundamental obstacle.This Account describes the photon-management capabilities of acenes and addresses these fundamental losses enroute toward enhancing PV performances.For high-energy photons that exceed the semiconductor’s bandgap energy,singlet fission(SF)is a down-conversion pathway to mitigate thermalization losses.SF is a process in organic materials,in which a singlet excited state is split into two independent triplet excited states,effectively doubling the number of charge carriers.Pentacenes stand out among acenes due to their exergonic nature of SF.Numerous molecular pentacene dimers have been synthesized to elucidate the relationship between structure and enhancing SF efficiency.A broader light-harvesting range of SF materials is realized by covalently attaching complementary absorbing energy donors to set up energy donor−acceptor conjugates.Förster resonance energy transfer(FRET)is operative in these energy donor-acceptor conjugates,effectively extending the absorption of SF materials,as the energy donor efficiently transfers its absorbed excitation energy to the energy acceptor.Our studies on various binding motifs show that FRET efficiency depends not only on parameters like the energy donor−acceptor distance and spectral overlap but also on subtle factors such as the alignment of transition dipoles,which significantly affect the energy transfer dynamics and efficiency.Turning to low-energy photons,triplet−triplet annihilation up-conversion(TTA-UC)provides a means of light up-conversion and,thereby,the reduction of sub-bandgap losses.In TTA-UC,a singlet excited state that is potent enough to generate charge carriers is formed by combining two triplet excitons.It is effectively the reverse process of SF.The higher triplet energy of tetracene and an endergonic SF renders them highly effective for TTA-UC.We focus on various tetracene-based systems that maximize TTA-UC efficiency.Besides TTA-UC,two-photon absorption(TPA)is yet another mechanism to leverage below-bandgap photons.It is a nonlinear optical(NLO)process,and acenes reveal NLO properties that are essential for extending light absorption into the near-infrared and still powering SF.We demonstrate in our proof-of-concept studies how TPA further broadens the application potential of acenes for PV systems.The strategies outlined in this Account illustrate that acenes are valuable for addressing mechanistic losses in conventional solar cells.In the final section,we examine light storage following SF by means of interfacial electron transfer.Efficient charge-injection powered by SF materials still requires more research before being implemented in large-scale PV designs.Overall,the advances discussed in this Account not only highlight the pivotal role of acenes as model systems to investigate photon down-and up-conversion processes but also paint a promising picture that more efficient solar energy conversion schemes exceeding the detailed-balance limit can be realized by implementing these materials.展开更多
Luminescence quenching in aqueous environments poses a challenge for practical applications.Lanthanide-doped up-conversion nanoparticles(UCNPs),representative of near-infrared(NIR)-emitting phosphors,typically utilize...Luminescence quenching in aqueous environments poses a challenge for practical applications.Lanthanide-doped up-conversion nanoparticles(UCNPs),representative of near-infrared(NIR)-emitting phosphors,typically utilize Yb3+ions as sensitizers,requiring 980 nm light.This wavelength coincides with the transitions of water molecules,interfering with population dynamics,and continuous irradiation causes unintended heating.Although Nd3+ions,which absorb at 800 nm,serve as alternative sensitizers,their practical use is limited by low quantum yield(Q.Y.).In this study,we developed water-insensitive down-shifting nanoparticles(WINPs)functioning within the NIR-Ⅰrange(700-900 nm)to avoid water interference.Characterization through single-particle-level spectroscopy demonstrated water-insensitive properties,with identical powers density and lifetime profiles under both dry and water conditions.The WINPs achieved a high Q.Y.of 22.1±0.9%,allowing operation at a detection limit power 15-fold lower than UCNPs,effectively eliminating background noise and enhancing overall performance.To assess diagnostic potential,we validated WINP-based lateral flow immunoassay(LFA)for detecting avian influenza viruses(AIVs)in 65 opaque clinical samples,achieving 100%sensitivity and an area under the curve(AUC)of 1.000 at only 100 mW cm^(-2).These findings highlight the potential of WINPs as water-insensitive NIR phosphors that can operate at low power,even in water-rich environments.展开更多
Luminescence anti-counterfeiting derives from the easily changeable luminescence behaviors of luminescence materials under the regulation of various external stimuli(such as excitation light,chemical reagent,heat,and ...Luminescence anti-counterfeiting derives from the easily changeable luminescence behaviors of luminescence materials under the regulation of various external stimuli(such as excitation light,chemical reagent,heat,and mechanical force,etc.)and luminescence lifetime,which plays an important role in preventing forgery of currency,artworks,and product brands.According to the numbers of changes of anti-counterfeiting labels under various regulation conditions,luminescence anti-counterfeiting can be classified into three levels from elementary to advanced:single-level anti-counterfeiting,double-level anti-counterfeiting,and multilevel anti-counterfeiting.In this review,the recent achievements in luminescence anti-counterfeiting are summarized,and the regulation of various factors to anti-counterfeiting labels is discussed.Finally,existing problems,future challenges,and possible development directions are proposed in order to realize facile,quick,low-cost,environmentally friendly,and difficult-to-replicate advanced luminescence anti-counterfeiting.展开更多
文摘In this study, a low complexity frame-rate up conversion method using compressed domain information for H.264 decoder is proposed. In the proposed scheme, the motion vectors （MVs） are estimated using constant acceleration motion model, and the MVs regarded as no credibility are corrected, and the interpolation method is applied on the basis of the macroblock （MB） coded types. Applied to the H.264 decoder, the proposed method provides high quality interpolation frames and an obvious decrease of the block artifacts.
文摘High efficiency frequency up conversion in trivalent erbium ion doped new fluoride glass matrix (ZnF 2 AlF 3 PbF 2 LiF) was investigated. Under 950 nm laser diode excitation, the glasses gave very intense green, weak red and violet emissions. The up conversion mechanism is discussed. In addition, the infrared transmittance spectrum, the Raman spectrum and the lifetime of the trivalent erbium states in the samples were measured. The results illustrate the large potential of these new glasses for photonic applications.
基金supported by the National Natural Science Foundation of China(11774046,12074373,52072361,51732003,52172083)the Key Research and Department of Science and Technology of Jilin Province(20230101012JC).
文摘Current optical storage technologies utilizing phosphor media face challenges in achieving rapid and precise data recording with visible or infrared light,primarily due to the constraints of traditional charging techniques.Here,we introduce a cutting-edge method termed up-conversion charging(UCC)to address these challenges,enabling rapid and high-resolution data storage in phosphors.Our study focuses on the unique two-step ionization and non-linear charging characteristics of UCC in storage phosphors,specifically in a gallate composition Gd3Ga5O12:Cr3+.Remarkably,this technique enables data writing with high solution,requiring only 0.01 s of exposure per bit when utilizing a portable laser engraver equipped with visible-emitting diode lasers.The present strategy not only enhances recording efficiency but also ensures long-term data retention and superior rewritability.Moreover,we illustrate the versatility of UCC storage across various material systems through thermally-and optically-stimulated luminescence.Our outcomes highlight the transformative potential of the UCC method in advancing optical storage applications,offering significant improvements in the development of information storage solutions.
文摘This paper reports the preparation of yttrium oxide(Y_(2)O_(3))doped with various concentrations of Er^(3+)using high temperature synthesis method.Photoluminescence(PL)emission spectra of the samples were recorded at an excitation of 980 nm laser source.Two prominent peaks centered at 484 nm and 574 nm were found and attributed to the^(2)P3/2→^(4)I_(11/2)and^(4)S_(3/2)→^(4)I_(15/2),respectively.The sample with 2.5 mol%of Er^(3+)provided the optimum intensity in emission spectra.The sample with optimum PL emission was investigated for its thermoluminescence(TL)glow curve exhibited the second order kinetics.The peak TL intensity was found around 236°C,i.e.,towards high temperature which supports the fact of formation of deeper traps.Therefore,the material taken may be regarded as a good candidate for light emitting diode(LED)applications.
文摘CONSPECTUS:Efficient photovoltaics(PV)require capturing and converting solar energy across a broad range of energy.Losses due to thermalization and sub-bandgap photons place,however,significant boundaries on the performance of solar cells.For conventional singlejunction cells,the theoretical maximum power conversion efficiency is capped at 33%,a constraint known as the detailed balance limit.Realizing the full potential of PVs requires developing novel strategies to overcome this fundamental obstacle.This Account describes the photon-management capabilities of acenes and addresses these fundamental losses enroute toward enhancing PV performances.For high-energy photons that exceed the semiconductor’s bandgap energy,singlet fission(SF)is a down-conversion pathway to mitigate thermalization losses.SF is a process in organic materials,in which a singlet excited state is split into two independent triplet excited states,effectively doubling the number of charge carriers.Pentacenes stand out among acenes due to their exergonic nature of SF.Numerous molecular pentacene dimers have been synthesized to elucidate the relationship between structure and enhancing SF efficiency.A broader light-harvesting range of SF materials is realized by covalently attaching complementary absorbing energy donors to set up energy donor−acceptor conjugates.Förster resonance energy transfer(FRET)is operative in these energy donor-acceptor conjugates,effectively extending the absorption of SF materials,as the energy donor efficiently transfers its absorbed excitation energy to the energy acceptor.Our studies on various binding motifs show that FRET efficiency depends not only on parameters like the energy donor−acceptor distance and spectral overlap but also on subtle factors such as the alignment of transition dipoles,which significantly affect the energy transfer dynamics and efficiency.Turning to low-energy photons,triplet−triplet annihilation up-conversion(TTA-UC)provides a means of light up-conversion and,thereby,the reduction of sub-bandgap losses.In TTA-UC,a singlet excited state that is potent enough to generate charge carriers is formed by combining two triplet excitons.It is effectively the reverse process of SF.The higher triplet energy of tetracene and an endergonic SF renders them highly effective for TTA-UC.We focus on various tetracene-based systems that maximize TTA-UC efficiency.Besides TTA-UC,two-photon absorption(TPA)is yet another mechanism to leverage below-bandgap photons.It is a nonlinear optical(NLO)process,and acenes reveal NLO properties that are essential for extending light absorption into the near-infrared and still powering SF.We demonstrate in our proof-of-concept studies how TPA further broadens the application potential of acenes for PV systems.The strategies outlined in this Account illustrate that acenes are valuable for addressing mechanistic losses in conventional solar cells.In the final section,we examine light storage following SF by means of interfacial electron transfer.Efficient charge-injection powered by SF materials still requires more research before being implemented in large-scale PV designs.Overall,the advances discussed in this Account not only highlight the pivotal role of acenes as model systems to investigate photon down-and up-conversion processes but also paint a promising picture that more efficient solar energy conversion schemes exceeding the detailed-balance limit can be realized by implementing these materials.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(NRF-2023R1A2C2003128).
文摘Luminescence quenching in aqueous environments poses a challenge for practical applications.Lanthanide-doped up-conversion nanoparticles(UCNPs),representative of near-infrared(NIR)-emitting phosphors,typically utilize Yb3+ions as sensitizers,requiring 980 nm light.This wavelength coincides with the transitions of water molecules,interfering with population dynamics,and continuous irradiation causes unintended heating.Although Nd3+ions,which absorb at 800 nm,serve as alternative sensitizers,their practical use is limited by low quantum yield(Q.Y.).In this study,we developed water-insensitive down-shifting nanoparticles(WINPs)functioning within the NIR-Ⅰrange(700-900 nm)to avoid water interference.Characterization through single-particle-level spectroscopy demonstrated water-insensitive properties,with identical powers density and lifetime profiles under both dry and water conditions.The WINPs achieved a high Q.Y.of 22.1±0.9%,allowing operation at a detection limit power 15-fold lower than UCNPs,effectively eliminating background noise and enhancing overall performance.To assess diagnostic potential,we validated WINP-based lateral flow immunoassay(LFA)for detecting avian influenza viruses(AIVs)in 65 opaque clinical samples,achieving 100%sensitivity and an area under the curve(AUC)of 1.000 at only 100 mW cm^(-2).These findings highlight the potential of WINPs as water-insensitive NIR phosphors that can operate at low power,even in water-rich environments.
基金National Natural Science Foundation of China,Grant/Award Numbers:21835002,21621001111 Project,Grant/Award Number:B17020。
文摘Luminescence anti-counterfeiting derives from the easily changeable luminescence behaviors of luminescence materials under the regulation of various external stimuli(such as excitation light,chemical reagent,heat,and mechanical force,etc.)and luminescence lifetime,which plays an important role in preventing forgery of currency,artworks,and product brands.According to the numbers of changes of anti-counterfeiting labels under various regulation conditions,luminescence anti-counterfeiting can be classified into three levels from elementary to advanced:single-level anti-counterfeiting,double-level anti-counterfeiting,and multilevel anti-counterfeiting.In this review,the recent achievements in luminescence anti-counterfeiting are summarized,and the regulation of various factors to anti-counterfeiting labels is discussed.Finally,existing problems,future challenges,and possible development directions are proposed in order to realize facile,quick,low-cost,environmentally friendly,and difficult-to-replicate advanced luminescence anti-counterfeiting.
