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Hoi nghi Khoa hoc ky niem 35 ndm Vien Khoa hoc vd Cong nghi Viet Nam - Hd Not 10 2010<br /> <br /> <br /> CAC VAT LIEU QUANG DIEN TlT VA QUANG TlT NANO<br /> Nguyen Quang Liem<br /> Vien Khoa h9c vat lieu, VKHCNVN<br /> 18 Hoang Qu6c Viet, Cau Giay, Ha Noi<br /> Email: liemnq@ims.vast.ac.vn<br /> Tom tat:<br /> Bdo cdo ndy trinh bdy nhiing kit qud nghiin ciru vi vdt lieu quang diin tir vd<br /> quang tu nand Irong thdi^ gian gdn ddy a Phdng Vdt lieu quang diin tu, Viin<br /> Khoa hgc Vdt lieu, bao gdm cd kit qud nghiin ciru cdng nghi chi tgo cdc chdm<br /> lugng tu bdn ddn (CdSe, CdTe, InP, CuInS2) phdt huynh qugng hiiu sudt ego, edc<br /> nghiin^ciru cdu trite, linh chdt qugng vd dinh hirdng irng dung cdc chdm luo'ng tir<br /> bdn ddn trong ky thudt ddnh ddu huynh qugng ndng-y-sinh, trgng linh kiin chiiu<br /> sdng rdn, ciing nhu trinh bdy vi triin vgng phdt triin ciia linh vuc nghiin ciru<br /> trgng bdi cdnh hgp tdc nghiin ciru vdi cdc ldp thi khgg hgc khdc thude cdc viin<br /> nghiin ciru/trudng dgi hoc trong nude vd qudc ti.<br /> Abstract:<br /> This report highlights the recent results on the studies of opto-electronic and<br /> photonic nanomaterials in the Lab of Opto-electronic Materials, Institute of<br /> Materials Science, including the results on the synthesis of highly luminescent<br /> semiconductor quantum dots (CdSe, CdTe, InP, CuInS2), their structural and<br /> optical properties and the studies orient lo the applications of such nanomaterials<br /> in agricultural-medical-biological labelings, in solid state lighting devices, as<br /> well as prosperous development of the field in the actively domestic and<br /> international collaborations.<br /> <br /> <br /> I. MO DAU<br /> Trong nhung nam gin day, vat lieu nan6 da va dang tra thanh dii tugng nghien ciin s6i<br /> dpng do nhirng tinh chit dac bipt. Trong do, hai tfnh chit dang quan tam xuit hien do ciu true<br /> nan6 la (i) s6 nguyen tir tren bl mat hat vat lieu chiim ti le lan so vai s l nguyen tir phan b l<br /> ben trong v^t lieu (h^t tinh thi co kich thuac 1 nm chi chua -30 nguyen tir voi hiu hit cac<br /> nguyen tir nam tren be mat; kich thuac 4 nm chira 4000 nguyen tir vai 40% sl nguyen tir nim<br /> tren be mat; kich thuoc 10 nm chira khoang 30000 nguyen tir vai 20% nim tren bl mat) va<br /> (ii) hieu ung giam ham hat tai dien khi kfch thuac hat vat lieu nho so sanh dugc vai ban kinh<br /> Bohr ciia exciton. Do vay, cac hieu ung/cac qua trinh hoa-ly, quang dien tir va quang tir lien<br /> quan toi kich thuac hat nh6 va trang thai bl mat cin dugc dac biet luu y khi nghien cim vat<br /> lieu CO cau tnic nan6. Khi quan tam tai hieu iing giam ham lugng tir, vat lieu thuang dugc gpi<br /> la cac cham lupn| tir, thuang co kfch thuac khoang mpt vai din mpt vai chyc nan6 met (tuy<br /> thupc vao ban chat vat lieu/ ban kinh Bohr ciia exciton dl c6 dugc hieu irng lugng tir hoa ba<br /> chieu cac trangjhai ciia he hat tai dien trong vat lieu d6). Hien nay, chim luang tir ban dan<br /> thuoc hp ban dan hgp chat II-VI nhu CdSe, CdTe dugc nghien cim cbl tao thanh c6ng nhit,<br /> cho cac tinh chat cau tnic cung nhu tinh chit quang vugt trpi [so vai mpt sl loai chim lugng<br /> tu khac nhu InP thupc hp hgp chit III-V]. Vl mat c6ng nghe dl chi tao vat lieu'tinh thi nan6,<br /> da CO nhimg t6ng ket rat c6 y nghTa, so sanh danh gia vl uu dilm/han chi ciia timg loai c6ng<br /> nghe [1,2]. Vai phuang phap hoa-ly, c6 thi kl mpt sl cong nghe diln hinh cho phep chi tao<br /> cac tinh the nano/cac cham lugng tir ban dan CdSe, CdTe chit luang cao nhu phuang phap<br /> gia nhiet hon hgp tien chat co kim (heatmg-up) [3], phuang phap phun tiln chit Cd va^Se. Te<br /> <br /> 37<br /> Tiiu ban: Khoa hoc Vdt lieu ISBN: 978-604-913-01 !-3<br /> <br /> <br /> vao dung djch nong (hot-injection) [1,^-6], phuong phap gia nhiet nhanh vai phan ung xa)' ia<br /> lien tyc trong dong chay (micro-fluidic heating) [7], phuang phap cbl tao trong m6i tru6n|<br /> nuac (aqueous phase sjnthesis) [8,9],... Trong cac phuong phap nay, cac chit boat dpng be<br /> mat (surfactant) da dugc sir dyng mpt each hgp ly vai cac tien chat thanh phin dl co the dieu<br /> khiln kich thuac va hinh dang ciia cac tinh the nan6/cham lugng tir.<br /> Qua trinh phat triln va nhirng thanh tyu c6ng nghe che tao cac chim lugng tir ban dan<br /> CdSe dugc tom tit nhu sau: Tmac nam 1993, nhieu nhom nghien cuu da e6ng b6 ket qua che<br /> tao cac chim lugng tir CdSe tir nguyen lieu ban dau khac nhau (ca hgp chat v6 ea va hiru ca,<br /> CO kim), nhung hieu suit phan ung tao san pham thap, phan b6 kfch thuac hat rong, hieu suat<br /> huynh quang thip (< vai %); Nam 1993, nhom Bawendi (Dept. of Chemistry, Massachusetts<br /> Institute of Technology) da c6ng bl ehl tao thanh c6ng cham lugng tir CdSe vai kich thuac<br /> 1,2 - 11,5 nm, co dp sai lech phan b l kich thuac - 5 % sau qua trinh chpn loc, co hieu suat<br /> lugng tir phat quang kha cao (9.6%) [3]. Day la cong nghp dot pha, (c6ng b6 [3] dugc trich<br /> din ban 1300 lan) cbl tao chim lugng tir CdSe bing mpt lin phan ung (single reaction), tren<br /> ca sa phan buy nhiet cac tiln chit ca kim (cadmium dimethyl Cd(CH3)2 va trioctylpbospbine<br /> selenium TOPSe) dl xay ra phan ung tuc thod giira Cd va Se trong dung m6i a nhiet dp cao<br /> (trong khoang 280 - 360 °C); Nam 1996, bing viec bpc lap vo ZnS cho cac chirn lugng tir<br /> CdSe dl thy dpng boa cac trang thai bl mat, nhom Guyot-Sionnest da nang hieu suat lugng tir<br /> huynh quang ciia chim lugng tir CdSe len 50%) [10]; Nam 2000, nhom tac gia Peng (Dept. of<br /> Chemistry and Biochemistry, Univershy of Arkansas) khi phan tfch phan ung hinh thanh<br /> CdSe da nhan thiy ring viec sir dyng Cd(CH3)2 la rat dgc, rat dat, kem ben a nhiet dp ph6ng,<br /> de chay n6 a nhiet dp cao trong khi phan ung de tao CdSe do giai phong mpt lugng khi lan.<br /> Vi vay, kh6ng the san xuat dugc lugng Ion cham lugng tir CdSe tir nguyen lieu ca kim ciia Cd<br /> [11]. Thanh c6ng c6 tinh dot pha de khac phyc nhirng ban che tren da dugc Peng va cpng sy<br /> thuc hien: che tao cham lugng tir CdSe chat lugng cao tir cac hgp chat v6 ca it dgc ban nhu<br /> CdO, CdCl2, CdC03..., vod kich thuac tir 1,5 nm den 25 nm co dp sai lech phan bo kich thuac<br /> khoang 5-10% (kh6ng can phai thyc hien ket tua chpn Ipc) va hieu suat lugng tir huynh quang<br /> dat 20-30% [5]. Hon nira, day la phuang phap dugc thyc hien trong he kin va kh6ng can tach<br /> cac phuc chat trung gian ciia Cd truac khi phan ung, nen no dugc xem la phuang phap boa<br /> sach (green chemistry) de che tao lugng lan cham lugng tir ban dan chat lugng cao.<br /> 0 Viet Nam, mpt s6 phong thi nghiem da trien khai nghien cuu che tao cac cham lugng tir<br /> CdS ya CdSe [12,13]. Phong thi nghiem Vat lieu quang dien tir thugc Vien Khoa hpc Vat lieu<br /> da trien khai cac nghien cim che tao, tfnh chat cau tnic va tfnh chat quang ciia cac loai cham<br /> lugng tir CdSe, CdTe, InP, CulnS2 phat huynh quang hieu suat cao nham mpt s6 img dyng<br /> trong danh dau huynh quang n6ng-y-sinh [14] va trong linh kien chilu sang rin. Ly do bit<br /> buoc de lya chpn nghien cim cac cham lugng tir ban dan tren la do nang lugng viing cim ciia<br /> chiing tuong ung vod viing ph6 hing ngoai gin, khi c6 hieu iing giam ham lugng tir (kich<br /> thuac nano met) chiing se phat huynh quang viing ph6 kha kiln, thuan tien cho cac ung dyng.<br /> Tinh chat phat quang hieu suat cao ciia vat lieu c6 kich thuac nan6 va dac biet la chim<br /> lugng tir ban dan dugc quan tam nghien cuu nham hien thuc hoa mgt s l ung dyng. Mgt trong<br /> cac ung dyng rat co y nghTa la lam chat danh dau huynh quang y-sinh (biolabeling) va dilu trj<br /> djnh vj (targeting treatment) [15-20]. Ben canh d6, chim lugng tir ban dan dugc cbl tao bing<br /> c6ng nghe ngay cang hoan thien, co gia thanh hgp ly, cho phep cac irng dyng co yeu ciu<br /> lugng sir dyng Ion ban, vi dy nhu trong cac linh kien quang dien tir. Vi vay, hien nay cac<br /> cham lugng tir ban dan dang dugc quan tam nhu la vat lieu huynh quang trong mpt ciu tnic<br /> linh kien chieu sang ran - mpt cau tnic ^Im c6 dilt phat quang (LED) va vat lieu huynh<br /> quang hieu suat cao c6 the hip thy mpt phan anh sang phat ra tir LED chuyen thanh anh sanh<br /> a viing ph6 mong mu6n, gop phin lam cho anh sang ting hgp phat ra tir t6 hgp LED+bpt<br /> huynh quang co mau sac mong muln [21-25], va trong cau tnic ciia linh kien chuyin boa<br /> nang lugng mat trod - cac pin mat trod cau tnic lai polymer/chim lugng tir [26,28].<br /> 38<br />  Hgi nghi Khoa hoc ky niim 35 ndm Vien Khoa hoc vd Cong nghe Viet Nam - Hd .\di 10 2010<br /> <br /> <br /> Bao cao nay trinh bay cac kit qua nghien ciin gan day ciia Phong Vat lieu quang dien tir,<br /> Vien Khoa hpc Vat lieu, ve vat lieu quang dien tir va quang tir nan6 bao g6m ca ket qua<br /> nghien cuu c6ng nghe che tao cac cham lugng tir ban dan CdSe, CdTe, InP, CuInS2 phat<br /> huynh quang hieu suat cao, cac nghien cuu cau tnic, tfnh chat quang va djnh huong ung dyng<br /> cac cham lugng tir ban dan trong ky thuat danh dau huynh quang d6i tugng n6ng-y-sinh,<br /> trong linh kien chieu sang ran, cirng nhu trinh bay ve trien vpng phat trien cua ITnh vuc nghien<br /> cim trong boi canh hgp tac nghien cuu vod cac tap the khoa hgc khac thupc cac vien nghien<br /> cim/tmang dai hpc trong nuac va qu6c te. Cac phuang phap c6ng nghe che tao/ t6ng hgp vat<br /> lieu va nghien cuu cau tnic, nghien cuu tinh chat quang,... ciing nhu cac nghien ciin tiep can<br /> img dyng, dac biet la cac iing dyng nham khai thac hieu suat phat quang cao dugc trinh bay<br /> chi tiet trong mgt so cong b6, bao cao thyc hien de tai khac [6,12-14,29-33].<br /> <br /> II. KET QUA VA THAO LUAN<br /> <br /> 1. Mot so ket qua nghien cuu che tao cac cham luong tu ban dan<br /> Hinh 1 trinh bay anh huynh quang ciia mpt s6 loai cham lugng tir chiing t6i da cbl tao<br /> dugc: CdSe/ZnS, CdTe/CdS, InP/ZnS. Co thi thiy chit lugng ciia cac chim lugng tir cbl tao<br /> dugc rat tot, the hien qua hieu suat huynh quang cao (>30%)) cho phep thiy ro huynh quang<br /> ngay duod anh sang trong phong. Cac chim lugng tir loai CdSe/ZnS hoac CdSe/CdS dugc chi<br /> tao trong dung m6i bun ca co nhiet dp s6i cao phu thupc rit ro ret vao trang thai bl mat ciing<br /> nhu cac ph6i tir bao bpc (ligand). Trioctylpbospbine oxide (TOPO) va hexadecylamine<br /> (HDA) cac la ph6i tir hiin ea thy dpng hoa mpt phin cac lien kit ha tren bl mat, cho phep<br /> cham lugng tir CdSe phat quang vai hieu suit lugng tir kha cao tod vai chuc phin tram. Tuy<br /> nhien, lap vo v6 ca 6n djnh va phii hgp ban trong rit nhilu iing dyng thyc tl. Tren ca sa phii<br /> hgp mang va kha nang giam ham hat tai (dien tir va lo tring) do nang lugng viing cim lan<br /> hon, CdS, ZnS va ZnSe da dugc sir dyng de tao lap v6 cho chim lugng tir CdSe, dang vo dan<br /> (bing cac vat lieu CdS, ZnSe hoac ZnS) hoac v6 kep (hai lop CdS/ZnS hoac ZnSe/ZnS). Peter<br /> Reiss va cpng su da rit thanh c6ng trong c6ng nghe bpc vo chim lugng tir CdSe bing mpt lap<br /> ZnSe hoac ZnS hoac hai lap ZnSe/ZnS hoac CdS/ZnS, cho phep huynh quang dat hieu suit<br /> lugng tir 60 - 85% [34]. Hien tai, chiing t6i dang co quan he hgp tac nghien cuu rit hieu qua,<br /> dac biet la trong nghien cuu cong nghe t6ng hgp cac loai chim lugng tir ban din, vai phong<br /> thi nghiem ciia Peter Reiss (CEA/Grenoble), da co NCS chung, c6 c6ng b l chung [6,29-33].<br /> Dac biet, chiing t6i da cbl tao thanh cong cac chim lugng td CdSe/CdS va CdTe/CdS trong<br /> m6i truang nuac cho hieu suat phat huynh quang cao, rit thuan tien cho nhirng ung dyng<br /> danh dau huynh quang nong-y-sinh [13,14].<br /> <br /> <br /> <br /> <br /> a) ^ WMb) wm^m^^am^mm^c)<br /> Htnh 1; (a) mdt phdn ciig hi thiet bi chi tgo vd sdn phdm chdm lugng tu CdSe/ZnS, (b) cdc<br /> chdm lugng tu CdTe/CdS tan trong nude vd (c) InP/ZnS. Vdi chdt lugng tdt, hiiu sudt lugng<br /> tuphdt quang cao, cdc chdm lugng tu huynh quang ro ngay dudi dnh sdng Irong phdng<br /> <br /> <br /> <br /> 39<br /> Tiiu ban: Khoa hoc Vdi lieu ISBN: 978-604-913-01 I j ^<br /> <br /> <br /> Vat lieu chim lugng tir InP dugc nghien cim che tao bang mgt s l phuang phap khac v^iva.<br /> Xuit phat tir nguIn nguyen lieu phosphor vang, m6i truong phan img la ethanol/toluene. dimg<br /> NaBH4 lam chit khir de tao In nguyen tir mai sinh cho phan img vai P, chiing t6i da che tao<br /> dugc cac chim lugng tir ban dan InP 6 nhiet dp phan iing thip -100 "C [31]. Sii dung PH3<br /> sinh ra tir phan img ciia Zn3P2 vai H2SO4 la ngu6n P cho phan ung vai In trong dung moi hiin<br /> CO CO nhiet dp soi cao octadecene (OD) cho phep che tao cac cham lugng tir InP'ZnS chat<br /> lugng cao, phat huynh quang trong viing 600 - 650 nm [36]. Khi sir dyng P(TMS)3 lam tien<br /> chit P, vai lugng Zn-stearate b l sung, c6 thi che tao dugc he th6ng mau chim lugng tir chat<br /> lugng tit, phat huynh quang hieu suit eao trong viing pho 485 - 586 nm [37].<br /> Phat triln nhirng kit qua nghien cim da thu dugc tren he vat lieu ban dan III-V pha tap ion<br /> dit hiim (GaN va InGaN pha Tm^^ va Eu^"" [38-42]), chiing t6i da ting hgp cac cham lugng<br /> tir InP pha tap Eu^^. Phuang phap boa ba buac trong mot binh phan img j;three-steps in one-<br /> pot method) da cho phep cbl tao thanh c6ng cac chim lugng tir InP:Eu^^ phat huynh quang<br /> tit. Cac kit qua nghien cim vat lieu chim lugng tir loai nay se dugc dang tren JACS [43].<br /> Vai loai vat lieu ba nguyen CuInS2, tren co sa nhimg kit qua nghien ciin che tao va tinh<br /> chit quang, kha nang sir dyng trong danh diu in vivo tren chugt ciia cham lugng tir CuInS^<br /> chit lugng cao cbl tao trong dung moi bun ca (OD va TOPO [30]), chiing t6i da phat trien<br /> nghien cuu cong nghe cbl tao cac chim lugng tir CuInS2 trong dung m6i diesel. Viec chpn<br /> dugc dung m6i diesel thuong phim rit re lam m6i tmong t6ng hgp vat lieu CuInS2 co y nghTa<br /> kh6ng chi vl mat kinh tl, ma diesel con thi hien uu viet vi vat lieu dugc che tao gan nhiet dp<br /> s6i ciia dung m6i, lam tang hieu suit tao san pham. Ket qua nghien cim che tao vat lieu va<br /> tinh chit quang cua cac chim lugng tir dugc trinh bay chi tiet trong bao cao khac [44]. CuInS2<br /> phat huynh quang hieu suit cao c6 thi dugc sir dung de danh dau huynh quang y-sinh kh6ng<br /> chira Cd [30] va ciing la loai vat lieu quan trpng trong cau true ciia pin mat trai, dac biet la pin<br /> mat trai lam viec trong m6i truang co nhieu tia vii try ban pha nhu a cac tram nghien cim<br /> khong gian [45-47].<br /> Noi chung, cac cham lugng tir sau khi che tao deu dugc khao sat vi hanh thai (bang ghi anh<br /> biln vi dien tir quet SEM hoac hien vi dien tir truyen qua TEM), cau true (bang phuong phap<br /> ghi gian do nhilu xa tia X va ph6 tan xa Raman, va trong mpt s6 tmong hgp bang ghi anh<br /> TEM phan giai cao), cho thay chat lugng tinh the che tao dugc tot. Do muc tieu sir dyng nhu<br /> la mpt vat lieu quang tir, quang dien tir, nen cac nghien cim tinli chat quang, cac qua trinh<br /> quang-dien tir trong vat lieu la c6 tinh bat buoc. Thyc chat, tinh chat huynh quang la mpt bieu<br /> hien quan trpng, t6 hgp he qua ciia cac yeu t6 chat lugng tinh the va sy thy dpng boa be mat<br /> cham lugng tir. Vi vay, tinh chat huynh quang t6t cho ket qua gian tiep ve chat lugng tinh the,<br /> nhung lai la myc tieu ciia cac nghien cim ve cham lugng tir ban dan nham ung dyng trong ITnh<br /> vyc quang tir va quang-dien tir.<br /> <br /> 2. Ket qua nghien cuu tinh chat quang<br /> Vai nhimg mau cham lugng tir ban dan chat lugng cao che tao dugc, chiing t6i da trien<br /> khai nhiing nghien cim ca ban ve cac qua trinh quang-dien tir, cac chuyen dai dien tir trong he<br /> th6ng mau dang keo (trong dung m6i) va dang cac hat xep chat (ran). Sau day, vai tirng loai<br /> cham lugng tir, chung t6i trinh bay mpt sl kit qua nghien cuu da thu dugc lien quan tai cac<br /> qua trinh quang dien tir, co nhan manh tai nhirng ket qua da dugc cong b6 qu6c te.<br /> Vai he th6ng cham lugng tir CdSe/ZnS, chiing t6i da nghien ciru hieu irng Stark a viing<br /> kich thuac nan6 met. Khi hinh dung mgt chim lugng tir co mpt dp phan eye nao do [48,6,49],<br /> dugc bao quanh bang mpt s6 phan tir ligand ciing co dp phan cue nhat djnh vai mpt dau phan<br /> cyc (quay vao phia cham lugng tir) va mpt dau kh6ng phan cyc (quay ra ngoai); tat ca dugc<br /> phan tan trong dung ni6i co dp phan cyc xac dinh se cho he qua cu6i ciing la cham lugng tir<br /> <br /> 40<br />  Hoi nghi Khoa hoc ky- niim 35 ndm Viin Khoa hoc vd Cong nghe Viet Nam - Hd Ngi 10 2010<br /> <br /> <br /> chju mgt dien truang hieu dyng ap dat len, gay su djch chuyen Stark ciia cac chuyen dai dien<br /> tir trong cham lugng tir. Vai ciing mpt loai cham lugng tir, cuong dp dien truong hieu dyng<br /> nay thay doi theo muc dp bao phii ciia cac phan tir ligand va dp phan cyc ciia dung m6i. Hinh<br /> 2 trinh bay hinh anh phan cyc ciia mpt cham lugng tir vai ligand xung quanh va dugc phan<br /> tan trong dung m6i co dp phan cue xac djnh. Kit qua nghien cuu hieu ung Stark a viing kfch<br /> thuac nan6 met thong qua vj tri dinh ph6 hip thy va huynh quang (Hinh 3) ciia chim lugng tir<br /> CdSe/ZnS phy thupc vao ligand va d6 phan cue ciia dung moi duac trinh bay chi tilt trong<br /> [6].<br /> <br /> <br /> <br /> <br /> H<br /> Total polirity from a complex of<br /> pol3rlz*dODs/Ligands and<br /> Solvant Hexane Toluene Chloroform Butanol Water<br /> Solvent<br /> <br /> Htnh 2; Hinh dnh cua mdt chdm lugng tu cd Hinh 3; Sit dich dinh phd hdp thu (Abs) vd<br /> dd phdn cue PQD vdi ligand xung quanh cd huynh quang (PL) cua chdm lugng tu CdSe<br /> dd phdn cue PIG ddt trong dung mdi ed dd phu thugc vdo PSQL vd sd Idn rua (ldm gidm<br /> phdn cue PSQL PLC ligands bao quanh chdm lugng tu CdSe)<br /> <br /> Lien quan tai qua trinh thy dpng boa bl mat ciia cac chim lugng tu ban dan hgp chit II-VI<br /> va III-V, chiing t6i nhan thiy ring c6 thi sir dyng cac ion H"" va OH" dl tmng hoa cac lien kit<br /> ha tren be mat ciia hat vat lieu (vi dy. cac lien kit ha cua ion Se^' va Cd^"" tren bl mat chim<br /> lugngjir CdSe). Cac ion nay co thi dugc sinh ra do chilu anh sang tir ngoai dl lam gay lien<br /> ket H^-OH^"^cua phan tu nuac; khi do, cac ion H^ va OH" mai sinh ra se tmng boa cac ion<br /> Se va Cd "" tuong ung. lam thy dpng boa cac trang thai bl mat, din tai sy tang hieu suit<br /> huynh quang cua cham lugng tir. Hinh 4 trinh bay hinh anh vl sy thy dgng boa cac lien kit ha<br /> tren be mat ciia chim lugng tu CdSe va kit qua tang cuang dp huynh quang khi chilu ang<br /> sang tir ngoai tren he th6ng mau chim lugng tir CdSe trong m6i tmong nuac. Mpt phin kit<br /> qua nghien cim qua trinh thy dpng boa bl mat bing phuang phap nay da dugc c6ng b l [49].<br /> <br /> 546<br /> :Cd+ - (OH) 544 E<br /> UV c<br /> CdSe QDs in H^O<br /> 10000 542 £<br /> e'-H^ UV irradiation Dl<br /> 540 ^<br /> 0)<br /> 538 I<br /> 536 ro<br /> Htnh 4; (a) sit thu ddng hod cdc liin kit Q.<br /> hd trin bi mdt ciia chdm lugng tu CdSe 1000 534<br /> khi chiiu dng sdng tu ngogi trin hi thdng 532<br /> mdu tan trgng mdi trudng nude; (b) su<br /> 500 1000 1500 2000 2500 3000<br /> tdng cudng dd vd dieh dinh huynh quang Irradiation Time (sec)<br /> (blue-shift) theg ihdi gign chiiu tu ngogi b)<br /> <br /> 41<br /> Tiiu ban: Khoa hoc I 'dt lieu ISBN: 978-604-913-01:<br /> <br /> <br /> Qua trinh thy dpng hoa be mat hieu qua dugc thyc hien tren hiu hit cac he thing charn<br /> lugng tir la tao dugc cau tnic I6i/v6 vai lap v6 dugc chpn la vat lieu ban din tuong tu nliung<br /> CO nang lugng 'viing cam rong hon. VI du cac cham lugng tir CdSe thuang dugc bpc vo bang<br /> CdS hoac ZnSe hoac ZnS hoac lap vo kep CdS/ZnS, ZnSe/ZnS. Bing ky thuat nghien ciin<br /> quang phi huynh quang phan giai thai gian, chiing t6i danh gia vai tro ciia cac trang thai be<br /> mat trong chuyin dai quang ciia cac cham lugng tir, tach biet dugc ro rang cac chuyen dai<br /> quang noi tai chim lugng tir va chuyen dai quang lien quan tai trang thai b l mat, xac dinh<br /> dugc dilu kien dl c6 phat quang hieu suat cao trong cac cham lugng tir ban dan. Ket qua<br /> nghien cuu chi tiet da dugc c6ng b6 [50].<br /> Vai he thing chim lugng tir InP va InP/ZnS, chiing t6i da nghien ciin hieu img truyen<br /> nang lugng va tmyln dien tich giira cac cham lugng tir. Ket qua thii vj nhan dugc la khi cac<br /> chim lugng tir dugc xip gin nhau, da co hieu iing truyen nang lugng th6ng qua tuong tac<br /> luang cue dien (~ 1/r^ - vod r la khoang each giira cac hat) va su truyen dien tich qua tiep xiic<br /> giira cac hat. Su tmyln nang lupng/dien tich dan tai hinh anh ph6 huynh quang phan giai thai<br /> gian djch dinh vl nang lugng thip theo thai gian tre sau xung kfch thfch, tuong ty nhu tai hgp<br /> cap donor-acceptor vai cac khoang each phan b6 khac nhau. Do khoang each giira cac cham<br /> lugng tir trong dung djch keo kha Ion nen tuong tac luong cue dien ciing nhu sy tmyen dien<br /> tich giira cac cham lugng tir kh6ng hieu qua, nen hau nhu kh6ng quan sat thay su djch dinh<br /> ph6 huynh quang phan giai thai gian (Hinh 5).<br /> <br /> Wavelengtii (nm) Wavelength (nm)<br /> 560 540 520 500 480 460 560 540 520 500 480 460<br /> (a) (b)<br /> Packed InP/ZnS QDs 1 dela/ed colloidal InP/ZnS QDs J<br /> vl delayed<br /> 4<br /> rb. units)<br /> <br /> <br /> <br /> <br /> l/Wv; 6<br /> \ 16<br /> tens ity arb. un its<br /> <br /> <br /> <br /> <br /> 10<br /> // \ 16<br /> 26<br /> 2.<br /> J V'f-\>A, \<br /> V<br /> 36<br /> 56<br /> V/ \ 36<br /> )j<br /> —<br /> ' ' 56 >. '-• U —''°°<br /> f / ,^1<br /> •• \<br /> ntens<br /> <br /> <br /> <br /> <br /> T ^ \<br /> fi/ 100<br /> <br /> <br /> c<br /> / / f / l \\<br /> FfU<br /> \ \ \<br /> _i<br /> _i<br /> Q. s v ^ Q.<br /> <br /> <br /> <br /> f/ .-^^^j-"''^^<br /> <br /> <br /> s___^"-^ A*<br /> .K<br /> jg5i^ ^ • \ \ .<br /> <br /> <br /> <br /> " "" 1 . 1 •^•^•^^^^^^^^^=^^3:<br /> I . I . I . 1 , 1 '.' -T'<br /> 2.2 2.3 2.4 2.5 2.6 2.7 2.2 2.3 2.4 2.5 2.6 2.7<br /> Energy (eV) Energy (eV)<br /> <br /> Hinh 5.' Phd huynh qugng phdn gidi thdi gian ciig chdm lugng tu InP/ZnS (a) dang rdn<br /> (cdc hgt xip gdn nhau) vd (b) dang keg (cdc hgt xg nhau). Dudng ke thdng trong hinh di chi<br /> ro su dich dinh phd trong mdu logi (a)<br /> Anh buong cua cong nghe cbl tao chim lugng tir InP dugc thi hien ro trong phi hip thy<br /> va huynh quang. Khi sir dyng lugng nho Zn trong thanh phin ciia tiln chit cbl tao InP, co thi<br /> duy tri phan b l kfch thuac hat kha nho -10% (tuong ung ban do rong phi -50 nm) vai hieu<br /> suat huynh cao kha cao (mpt s l miu dat -70%). Dilu quan trpng la khi c6 mpt lugng Zn tham<br /> gia trong thanh phan ciia chim lugng tir InP, no tra thanh sy chuin bj tot dl bpc v6 ZnS sau<br /> d6, dl tao ciu tnic I6i/v6 In(Zn)P/ZnS [37].<br /> Su on djnh kich thuac In(Zn)P trong thai gian hip phy ion Eu^"" tren be mat va sau do la<br /> <br /> 42<br />  Hoi nghi Khoa hoc ky niim 35 ndm Vien Khoa hoc vd Cong nghe Viet Nam - Hd Noi 10/2010<br /> <br /> <br /> khulch tan ion trong chim lugng tir va bpc v6 ZnS la dieu kien can thiet de che tao dugc<br /> chim lugng tir pha tap ion Eu^"" a kich thuac (viing ph6 hap thy va huynh quang) mong mu6n,<br /> cho phep nghien cuu hieu ung tmyen nang lugng giira vat lieu chii In(Zn)P va tap ion Eu^"".<br /> Kit qua nghien cuu cbl tao In(Zn)P va qua trinh pha ion Eu^"^ se dugc cong b6 [43]. Co the<br /> thiy ring, ve mat nghien cuu ca ban ciing nhu djnh huong ung dyng, he th6ng cham lugng tir<br /> pha tap ion dat hiem la d6i tugng t6t. C6 nhieu van de nghien cuu lien quan tai vj trf/phan b6<br /> cua cac ion dat hiem trong he vat lieu cham lugng tir, ca che huynh quang, cac qua trinh mat<br /> mat nang lugng sau khi kfch thfch, dong gop cua cac hat tai va sai hong mang trong qua trinh<br /> tai hgp phat quang, cac qua trinh tmyen nang lugng giira vat lieu chii (vi du cac cham lugng<br /> tir GaN va InGaN hoac InP) vai ion tap (vi dy Tm^^, Eu ^),... Ket qua nghien cuu cho thay<br /> mu6n CO phat quang hieu suat cao trong cac ion dat hiem thi phai ban che qua trinh tmyen<br /> nang lugng ngugc tit ion dat hiem a trang thai kich thfch ve nen vat lieu chii [39-42,51].<br /> <br /> Ve loai vat lieu cham lugng tir CuInS2 phat huynh quang hieu suat cao co the dugc sir dyng<br /> de danh dau huynh quang y-sinh kh6ng chua Cd, chiing t6i da tien hanh nhimg nghien cim<br /> cac chuyen dai dien tir phat quang va da xac djnh ca che huynh quang do tai hgp donor-<br /> acceptor, mpt ca che huynh quang ph6 bien trong vat lieu ban dan khoi, nhung van xay ra<br /> trong vat lieu co cau tnic nano [33].<br /> 3. Trien vong ung dung cac cham luong tir ban dan<br /> Mpt s6 ling dyng rat co y nghTa ciia cham lugng tir ban dan la Iam chat danh dau huynh<br /> quang (fluorescence labeling) cho doi tugng y-sinh (medicine-biolabeling) va gan day la d6i<br /> tugng n6ng san hoac virus trong san xuat n6ng nghiep (agricul-labeling), va dieu trj djnh vj<br /> (targeting treatment) [14-20]. Trong cac ung dung nay, uu diem kh6ng d6i h6i kich thich<br /> quang chpn Ipc va ben quang ciia cac cham lugng tir ban dan so vai chat mau hiin ca dugc<br /> khai thac. Ben canh do, cham lugng tir ban dan dugc che tao bang c6ng nghe ngay cang hoan<br /> thien, co gia thanh hgp ly, cho phep cac ung dyng c6 yeu cau lugng sir dyng Ion hon, vi dy<br /> nhu trong linh kien chieu sang ran [21-25]. Sau day, chiing t6i trinh bay nhirng van de lien<br /> quan toi hai loai ling dyng cua cham lugng tir trong danh dau huynh quang va lam vat lieu<br /> phat huynh quang hieu suat cao trong linh kien chieu sang ran, mgt s6 ket qua ban dau va<br /> trien vpng thuc hien a Viet Nam trong sy ph6i hgp giira cac don vj nghien ciin chuyen nganh.<br /> <br /> 3.1 ung dung cham luang tiir bdn dan trong ddnh ddu huynh quang<br /> Hinh 6 trinh bay anh hien vi ciia cac nam men dugc danh dau bang chim lugng tir ban dan<br /> CdSe/ZnS. Co the thay cac cham lugng tir ban dan CdSe/ZnS da phan b6 ben trong te bao<br /> nam men [12]. Day la nhirng nghien cuu khai dau, lam tien de tien tai nhirng nghien ciin danh<br /> dau dac hieu theo ca che khang nguyen-khang the. Hinh 7 trinh bay danh diu huynh quang<br /> HER2 phage theo nguyen ly khang nguyen-khang the [34]. Ket qua ebo thay chit lugng cham<br /> lugng tir CdTe do Vien Khoa hpc vat lieu che tao hoan toan dap ung cho ung dyng danh dau<br /> huynh quang, kh6ng khac cac cham lugng tir ban dan thuang pham. Ngoai van de tiet kiem<br /> (vi gia cham lugng tir ban din thuong pham -300 USD/mg, rit dit), viec cbl tao dugc chim<br /> lugng tir dat chat lugng cao c6 y nghTa tao su chu dpng, tu cung cap dugc chim lugng tir cho<br /> nhimg thi nghiem co thiet ke truac.<br /> <br /> <br /> <br /> <br /> 43<br /> Tiiu ban: Khoa hoc Vgl lieu ISBN: 978-604-913-01<br /> <br /> <br /> <br /> <br /> Hinh 6; Anh huynh quang cita li baa ndm Hinh 7; Anh huynh quang ciia HER2 phage<br /> men chirg chdm lugng tit CdSe/ZnS. Kich lien kit vdi chdm lugng tit CdTe. Kich thirdc<br /> thude dnh ~I0 mm x 10 mm [12] dnh ~10 mm x 10 mm [34]<br /> Bang sy hgp tac mang tinh bo sung, ky thuat danh dau huynh quang dac hieu tren ca so<br /> nguyen ly khang nguyen-khang the sir dung cac cham lugng tir do Vien Khoa hpc vat lieu che<br /> tao va cac khang the do Vien C6ng nghe sinh bpc che tao dang dugc trien khai nghien ciin<br /> manh me, nham co dugc img dyng cy the trong theo doi phat hien du lugng thu6c trir sau/bao<br /> ve thuc vat trong gao va mpt so loai hoa qua, du lugng chat tang trgng trong san pham thjt, va<br /> phat hien sam vims cum gia cam H5N1 [14].<br /> 3.2 Ung dung cham lugng tu bdn ddn trong linh kien chieu sdng rdn<br /> Linh kien chieu sang ran hien nay dang sir dyng mpt LED phat quang viing 440 - 480 nm<br /> dugc che tao tren co so vat lieu InGaN, vira lam nguon kich thich cho hot huynh quang<br /> (Y3Al50i2:Ce * - tuc YAG:Ce^*, trong do YAG la vat lieu nen hap thy anh sang xanh lam tir<br /> LED (B-LED), tmyen cho ion Ce^"^ la activator phat quang vimg phi 580 nm) vira la thanh<br /> phan ph6 de tron mau, cho nhiet dp mau mong mu6n [52]. Theo ly thuylt, sy iron mau se cho<br /> nhiet dp rnau (color temperature) va dp tra mau (color rendering index) ciia mpt linh kien loai<br /> tren t6t neu LED phat quang 480 nm va bot phat quang b l sung dai huynh quang dinh a 580<br /> nm. Tuy nhien, de LED phat quang 480 nm cin pha In ty le kha cao (> 30%o) trong thanh phin<br /> InGaN, la c6ng nghe kh6ng de dang do sy bay hoi ciia In trong qua trinh cbl tao vat lieu.<br /> (Day CO le la ly do vi sao cac LED Trung QuIc ban 6 nuac ta chii ylu phat quang viing 430 -<br /> 460 nm va rat kh6ng dong nhat).<br /> Khi sir dung cham lugng tir ban dan thay cho YAG:Ce, co mgt s l uu dilm sau: thir nhit, la<br /> hieu suat lugng tir huynh quang cao; thu hai, la co thi dilu chinli viing phi, b l sung cac dai<br /> ph6 can thiet de dat dp tra mau cao. Dii ring gia thanh hien nay cua cac chim lugng tir ban<br /> dan c6n rat cao (khoang 300 USD cho 1 mg diing trong danh diu huynh quang y-sinh - c6 thi<br /> do lugng sir dyng qua nho), nhung thuc tl chiing t6i da ehl tao vat lieu va thiy ring nlu<br /> lugng sir dung Ion se cho phep giam dang kl gia thanh, c6 thi sir dyng chim lugng tir ban dan<br /> lam ngu6n vat lieu quan trpng trong ky thuat chi tao cac linh kien chilu sang rin [53]. Hinh 8<br /> trinh bay mpt thir nghiem che tao nguIn sang rin tren ca sa di-lt phat quang 460 nm (B-<br /> LED) va hot cham lugng tir ban dan huynh quang 6 -600 nm.<br /> <br /> <br /> <br /> <br /> 44<br />  Hgi nghi Khoa hoc ky niim 35 ndm Viin Khoa hoc vd Cong nghe Viet Nam - Hd Noi 10/2010<br /> <br /> <br /> <br /> <br /> Hinh 8; Vi du vi ngudn sdng rdn tren ca sd<br /> chip B-LED vd chdm lugng tu CdTe/CdS [13]<br /> <br /> <br /> <br /> IIL KET LUAN<br /> Bao cao da trinh bay mpt s6 ket qua nghien cuu gan day ciia Phong Vat lieu quang dien tir,<br /> Vien Khoa hpc Vat lieu, ve c6ng nghe che tao cac chim lugng tir ban din CdSe, CdTe, InP,<br /> CuInS2 phat huynh quang hieu suat cao trong viing phi kha kiln, cac nghien ciin ciu tnic,<br /> tinh chat quang va djnh buong img dyng cac chim lugng tir ban dan trong ky thuat danh diu<br /> huynh quang nong-y-sinh, trong linh kien chilu sang rin. Chiing t6i da chii dgng, thanh c6ng<br /> trong c6ng^nghe cbl tao cac cham lugng tir ban din dat chit lugng cao, hoan toan dap ung<br /> nhu cau mau t6t cho cac nghien cim co ban, ciing nhu nhimg iing dyng dac biet, theo thilt kl<br /> truac. Trong khi trien khai huong nghien ciin vl cac chim lugng tir ban dan, chiing t6i da<br /> hinh thanh va phat trien t6t cac hgp tac nghien cuu vai cac tap thi khoa hgc khac thugc cac<br /> vien nghien cim/truang dai hpc trong nuac va quIc tl. 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