Raws li kev tshaj tawm xov xwm txawv teb chaws, lub teeb -emitting diodes (LEDs) yog qhov tsis zoo ntawm kev lag luam teeb pom kev zoo. Lawv ua hauj lwm zoo, dissipate tsawg tshav kub, thiab kav ntev. Tam sim no, cov kws tshawb fawb tab tom ua haujlwm ntawm cov khoom siv tshiab los ua kom cov LEDs muaj txiaj ntsig zoo dua thiab siv tau ntev dua rau kev siv hauv cov khoom siv hluav taws xob, tshuaj thiab kev nyab xeeb.
Researchers from the U.S. Department of Energy's (DOE) Argonne National Laboratory, Brookhaven National Laboratory, Los Alamos National Laboratory, and SLAC National Accelerator Laboratory report that they have prepared stable calcium for such LEDs Titanite nanocrystals. Research institutes from the Taiwan region of China also contributed to this research.
Perovskites yog ib chav kawm ntawm cov ntaub ntawv uas muaj cov qauv siv lead ua tshwj xeeb uas nqus thiab tawm lub teeb, ua rau lawv muaj txiaj ntsig hauv ntau lub zog- siv tau zoo, suav nrog lub hnub ci hlwb thiab ntau yam khoom siv.
Thaum perovskite nanocrystals yog thawj tus neeg sib tw rau hom tshiab ntawm cov khoom siv LED, lawv tau ua pov thawj tsis ruaj khov hauv kev sim. Pab neeg ua haujlwm ruaj khov ntawm nanocrystals hauv cov qauv porous hu ua hlau organic moj khaum, lossis MOFs luv luv. Raws li lub ntiaj teb- cov ntaub ntawv ntau thiab ua nyob rau hauv chav tsev kub, cov LEDs no muaj peev xwm muaj ib hnub ua kom qis dua - TVs thiab cov neeg siv khoom siv hluav taws xob, zoo dua gamma- cov khoom siv hluav taws xob, thiab txawm tias lub tshuab hluav taws xob rau tshuaj, kev soj ntsuam kev ruaj ntseg, thiab kev tshawb fawb tshawb fawb. Fais fab lub X-ray detector.
"We solved the stability problem of perovskite materials by encapsulating them in MOF structures," said Xuedan Ma, a scientist at the Center for Nanoscale Materials (CNM) in Argonne, DOE's Office of User Facilities, "Our research shows that this approach enables We can dramatically improve the brightness and stability of the luminescent nanocrystals."
Hsinhan Tsai, former JR Oppenheimer postdoc at Los Alamos University, added: "The interesting concept of incorporating perovskite nanocrystals in MOFs has already been demonstrated in powder form, but this is the first time we have successfully integrated them into the emissive layer of an LED. "
Cov kev sim yav dhau los los tsim cov nanocrystalline LEDs tau raug cuam tshuam los ntawm kev degradation ntawm nanocrystals rov qab rau hauv cov theem uas tsis xav tau, uas tshem tawm qhov zoo ntawm nanocrystals thiab txo qis lawv lub peev xwm raws li cov tswv yim LEDs. Cov teeb meem loj yog tsim los ntawm billions ntawm atoms. Cov ntaub ntawv zoo li perovskites yog tsim los ntawm ob peb mus rau txhiab tus atoms ntawm nanoscale thiab yog li coj txawv txawv.
Nyob rau hauv lawv txoj kev tshiab, pab neeg ruaj khov nanocrystals los ntawm fabricating lawv nyob rau hauv ib tug matrix ntawm MOF, zoo li lub pob tennis raug clamped los ntawm barbed hlau. Lawv siv lead nodes nyob rau hauv lub moj khaum ua hlau precursors thiab halide ntsev raws li cov ntaub ntawv organic. Cov tshuaj ntsev halide muaj cov tshuaj methylammonium bromide, uas cuam tshuam nrog cov hlau lead hauv lub moj khaum thiab sib sau ua ke nanocrystals nyob ib ncig ntawm cov hlau lead hauv matrix. Txij li thaum lub matrix khaws cov nanocrystals cais, lawv tsis cuam tshuam thiab degrade. Cov txheej txheem yog ua raws li ib qho - cov txheej txheem daws teeb meem uas tsis tshua kim dua li cov txheej txheem nqus tsev uas tau siv dav niaj hnub no los ua cov LEDs inorganic.
MOF-stabilized LEDs tuaj yeem tsim lub teeb liab, xiav thiab ntsuab thiab sib txawv ntawm txhua lub teeb.
"In this work, we demonstrate for the first time that perovskite nanocrystals stabilized in MOFs will create bright, stable LEDs in a variety of colors," said Wanyi Nie, a scientist at the Center for Integrated Nanotechnology at Los Alamos National Laboratory. "We can create different colors, improve color purity and increase photoluminescence quantum yield, a measure of a material's ability to emit light."
The research team used the Advanced Photon Source (APS) -- DOE's Office of Science User Facility in Argonne -- to perform time-resolved X-ray absorption spectroscopy, a technique that allowed them to discover changes in perovskite materials over time. Researchers can track the movement of charges through the material and learn important information about what happens when light is emitted.
"We can only do this with the powerful single X-ray pulse and unique temporal structure of APS," said group leader Xiaoyi Zhang in Argonne's X-ray Science Division, "We can track charged particles in tiny perovskite crystals. s position."
Hauv kev sim ua kom ntev, cov khoom ua tau zoo nyob rau hauv UV hluav taws xob, tshav kub thiab hluav taws xob tsis muaj degrading thiab poob nws lub teeb pom kev zoo thiab luminescence efficiency, qhov tseem ceeb rau kev siv xws li TVs thiab hluav taws xob detectors.
