High efficiency nitride based phosphores for white LEDs

Hele tekst

(1)J. Light & Vis. Env. Vol.32, No.2, 2008. 129. Pa pe-. High Efficiency Nitride Based Phosphors 'tor White. LEDS. Y.Q. LI*'** and H.T. HiNTZEN* tDepartuent of Chemical Engineering 8nd Chenistry Eindhoven Uhiversity of Teibnology. -NationallnstituteforMaterials Science. Received December 13, 2007, Accepted January 21, 2008. ABSTRACT in this overview paper, novel rare ;arth doped silicon nitride based phosphors forwhite LEDS app]ications have been. demonstrated. The lvminescenoe properties of orange-red mitting phosphors (M2Si5N8:Eu 2+) and green-t0+yellow emitting phosphors (MSi2N202:Ev2+, M = Ca, Sr, Ba) aTe discvssed in detaii with a focus on the relatonship beiween. tfle properties and structures. With high conversion efficiency in the near UVlblue region, along with high chemioaVphysical stability, Eu2･ - and Ce. - activated alkaline>earth silicon nitride and oxynitride materia]s are. excellent wavelength onversion phosphors for white LEDs.. KEYWORDS :. nitride, phosphor, Iuminesoen , white LEDS. 1. In:troducition. invented and attractcd much attention in recent years. Recently, bre akthroughs in inorganic light emitting diodes (LEDS) technologyD2) are significantly catelyzing. their unusual luminescence properties compared to oxide,. the development of energy eiicient and long lifetime solid-. sulphide and balide based phosphors or their. due to their high chemical and theunal stability, as well as. state lighting (SSL). Sohd-state lightmg technology has. combinations. It is just the presence of nitrogen in the host. now aheady penetrated in a variety of specialty. lattice that makes the rare-earth ions exhi'bit unique. applications, in effect, LEDS have completely cbanged the "world of luminance" , for exanrple automobile brake lights,. optical properties because of their bigh covalency (nephelauxetic eff'ect) and large crystal field splitting ") .. traf c signals, liquid crystal displays and mobile. In this paper, we will describe some of our research. backlights, flashlights and all mamer of architectural. projects on novel rare-earth acti'vated s:iilicon nitride based. sp otlightsP･) . In parti*cular, the invention of high-ef ciency. materials with an emphasis on the luminescen. blue-emitting InGaN-based LEDS makes realization of. properties of Eu2*- and Ce3+-doped akaline-earth sihoon. efficient, full-spechium white-lig:ht LEDs for general illumination possible by using conversion phosphors, and wll bring about a revolution in lighting industry ) .. nitride and oxynitride phosphors for white -LED. However, the excitation sources in LEDS are quite. 2. Experimental approaches Rare earth doped s icon nitride, oxynitride and. diffierent from the traditional sour s, such as mercury gas-discharge. Thus only a very limited number of present. a p plications.. carbide -nitride materials were synthesized starting from. phosphors can meet the mininum requirements for. akaline -earth metals and/or oxides, silicon nitride ,. white-light LED applications. Most traditional phosphox:s. aluniinum nitride , s icon carbide and rare-earth nitrides. carft be e iciently excited above 400 nm. In order to obtain high efficiency and better color rendering LEDs, the development of suitable green-, yellow- and red-. cr oxides by a solid- state reaction at high temperature. emitting phosphors is the great challenge. As a eonversion. phosphor for white phosphol'-converted LEDs, a strong abso'rption in the blue or near-uv re gion and a highly e icient conve sion for re-eroission into the green, yelbw. ranging from 1300-1650 'C in a N2/H2 atmosphere. The phase composition and (:. rstal structure were detelmined. by the powder X-ray di fraction techniques. Photoluminescen. properties were measured at room. temperature by a Perkin Elmer LS 50B spectrophotcmeter equipped with a Xe flash lamp. The. and red light are required. Therefore, to modify existing. conversion. and explore new phosphor materials with improved. was estirnated by dr'viding the luminescen. properties for use in white LEDS is extremely urgent.. the measured absorption of 465 nm radiation, and. Fortunately, a new dass of inorganic phosphors, viz. rare-earth-doped-silicon-nitride based materials, has been. 79. .e. quantun) efiiciency of the luminescence intensity by. comp aring the result with the value corresp ondingly. The llluminating Engineering Institute of Japan.

(2)

(3)

(4)

(5)

(6) 134. 」1Ligh‘｛隻防曽．Eκ軌ンわ∠32，ノVo．2，2008. Spe（惣al ra狙ge．GiVe豆the hig蓋qUant㎜ef＆Cien（収，鐵gh. （8）H，Y．Q．，vanSTEEN，」．EJ．，vanKREVELJ．WH．，. Che血CaiandthermalStab澱旬撫搬enearUV／blUeregiOn，. BO畑G．，DELS王NG，A．C．A．，DISALVO，E．」．，de. 威ongwi嶺goodoO即＆齪eoO即os遍on，ora登geTeδ. WITH G．㎝δHINTZEN，H．T．：Lu血escence. e血む血9 施S跳N8：Eu2＋（M ＝ Ca， S鴻 Ba） and green・. e血伽gMS洲202：E疑2＋（M＝Ba，S珍haveもumedou伽 begoodcandiδa七econversionphosphorsibruseinboth nearUVandb1蟻e−LEDs．1簸addi揺o無，撮anynewtem町 and mult㎏ary nit盃de based phoqphors wi撫 u追co遼ve追鉦onai or血proved proper量es aヱe e巡）e伽d to麦）e. 曲covered血the neaH玩Ure fbrwhi総LEDs．. 峯）rope廠es of red−e血t血9施Si5N8：露斌2申（M皿Ca，S蔦 Ba）工￡D conversio遼 phospho塑s，」、A丑oys Comp．堀．417（1−2），PP．273−279（2006）、. （9）慧，Y．Q．，DELSING，A．CA．，δe WITH，G．and HINTZEN，H．T．：L櫨esce総ce欝roper駐esofEu2＋一＆c犠vαteda］ka血e・e舳曲co簸・ox海崩deMS並026 N2＋鴻δ（M皿Ca，S鶉Ba）：apr・鋤曲9曲s・fn・vel LED conversion p五〇sphors，C強em．M＆te五，Vbi．17（12），. Re盆ences. pp．3242−3248（2005）．. （10）BLASSE，G．and GRABMAIER，B．C．：Lu血esce跳（1）TASO，」．Y．，Ed、：Light emi睡g diodes（LEDs）驚r. genera1還u鋤a琶o益，Update2002，0p宅oelec蟹onics I撮usねy Develop撮e煎Associa盤o澱，鴨s㎞gねD捻，DC （2002）．. （2）Zukauskas，A、，S蓋肥，M．S．and Gaska，R．：熱捜oduc嫉on. bDSo撚一State獄9烈額ng，Jo㎞W韮ey＆Sons，1撫c．，New yヒ）rk（2002）．. （3）NARUKAWA．，Y．二W姐艶鼓ght LEDs， Qpt記＆ P簸o斐Dnics News，No．4，pp．25−29（2004）．. （4）NAKAMURA， S．： Cεmdelaて窪ass hl帥一bま辻gh磁ess. hGaN！AtGaNδouble・heteros餓c継e blue一践ght− e麺甑g diodes，AppL P蓋y＄．Le枕．，Vbl．64（ま3），pp1687− 1689（生994）．. （5）v鋤 K認VEL，」．W．｝｛．， HIN了ZEN， H．T，. Ma鎗践曲，Sp血ger−V6rlag，Be翌㎞（1994）．. （11）van K昭VEL，」．WH．，van RU㎜EN，よWT．，㎜AL，H．，HIN㎎EN，H．T．an（至遡TSELAAR，R．： L㎜蚕escencepでope工雌eso￡もerbium・，ce薮㎜一，or europium・δopeδα・S機ON鵬teria蛤，」．So昼dState Chem．，Vbi．165，PP．王9−24，（2002）．. （12）X電，R．」．，MITOMO，M．UH猛DA，K．，XU，F．E and，. AKIMじNE，Y．：P薫epaヱa媛oR㎝δ1舳esceacesgec㍑a ・fα掘㎜一鍛囎鷹一e麟h一（R皿E雛，Tb，＆adP⇒codoped α一S測ONce翌鋤ics，」．Am．Cera皿．S㏄．，Vb｝．85（5），脚．1229一ま234（2002）．. （i3〉Li，Y、Q．：s㎞勲・e副1㎜搬escencepで・p曲es・｛n・vel 翠are−ea枕h dopeδs掛con ni髄de based ma七e疫曲，Ph．D．. 翫es蛤，E盆dhvoe豊U蚕versi旬of［艶（㎞010gy（2005）．. METSELAAR，R．ε狙d MEIJER［N風 A．：恥ng waveleng旗Ce鉄e曲sioninY＝Siつ一Nlnate滋als，」． A匪・ysC・mp．，Vb1．268（6），PP．272・277（i998）．（6）vε阻KREVEL，」．W．美｛．：0鍛new r＆re−earth dopedM−Si一. 母ONma鎗由蛤：L㎜血esce益ceprope慮esa追d o滋dぬo鍛re曲tance，Ph王）thesis，E熱dhoven U曲ersityof圧bch灘oiogy（2000）．. （7）H6PPE，HA．，LuTz，H．，MORyS，P，ScHNIcK，w．. 箏his pa茎）er is b＆sed o総 the aut薮oぎs）preseP』tatioB. εmd SE猛MEIER，A．：Lu皿血escence血Eu2＋doped. given＆tt振elst王ntemationa1Co㎡erenceo簸White. Ba2S島N8：登犠o翌escence 出e㎜olu血escence， and. LEDs and Solid State Ughting held魚1目okyo，Japan，. upconve灘sion，」．Phys．Chem．So銭d8，Vd．61，pp．2001−. o且Nove塑ber26t鼓凹30乞h，2007．. 2006（2000）．. Thelll襯i脇ing伽ginεθr∫ng1κs‘i鰭qヂ珈oη. 84.

(7)

No results found