Acta Phys. Sin. Vol. 61, No. 9 (2012) ) 1) 1) 2) 1) 1) (,, ) 2) (, ) ( ; )

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1 * 1) 1) 1) 2) 1) 1) (,, ) 2) (, ) ( ; ) (4, 4 -bis(2, 2 -diphenylvinyl)-1, 1 -biphenyl, DPVBi).. DPVBi nm, DPVBi,40nm, cd/m 2, 3.2%, (Commission Internationale de l Eclairage (CIE) co-ordinates) (0.15, 0.15). DPVBi 40 nm,., DPVBi nm. :,,, PACS: Fb, Le, Fi 1 (organic light-emitting device, OLED),,.,,. [1 4]. Zhou [1] NPB(N, N -bis-(1-naphthyl)-n, N - diphenyl-1, 1 - biphenyl-4, 4 -diamine), 12 nm ; Jiao [2] NPB/Alq (tri-(8-quinolinato) aluminum) ( nm),. [3],,. Xie [4] (4, 4 -bis(2, 2 -diphenylvinyl) -1, 1 - biphenyl, DPVBi, Idemitsu, Hosokawa, ) [5],, (40 nm), 1.78 cd/a; (10 nm) 4.68 cd/a,, Alq. [6], Alq, Alq. Alq 10 nm. DPVBi [5], NPB Alq ( 50 nm 6nm, * ( : 1010RJZA035), ( : 40 ) ( : , ). youzhiwu@163.com c 2012 Chinese Physical Society

2 Alq ) DPVBi, DPVBi. DPVBi nm,, ; DPVBi 40 nm,,. DPVBi 40 nm,, 3.2%( 4.3 cd/a), cd/m 2, 3.4 V, (Commission Internationale de l Eclairage (CIE) co-ordinates) (0.15, 0.15). 2 (indium tin oxide, ITO) [6],, Pa MoO 3 (0.5 nm) [7,8] NPB (50 nm), DPVBi(10 50 nm), Alq (6 nm), LiBq 4 (lithium tetra-(8-hydroxy-quinolinato) boron, 1nm) [9], Al (100 nm), : ITO/MoO 3 /NPB/DPVBi/Alq/LiBq 4 /Al, DPVBi 10 nm, 20 nm, 30 nm, 40 nm 50 nm A1, A2, A3, A4, A nm/s, 5nm/s,. (Libero Ltd.) PR650, (Keithley Ltd.) 2400,. 1 NPB, DPVBi Alq. 3 2 DPVBi (photoluminescence, PL) DPVBi (electroluminescence, EL). DPVBi nm EL DPVBi PL, 456 nm, DPVBi 50 nm EL 464 nm, PL 8nm. DPVBi EL., EL PL ( [10] ) ( [6] ) [11].,,, DPVBi A1, A2, A3 A4 EL, DPVBi 50 nm A5 EL., DPVBi, / [5] ;, 1 NPB, DPVBi Alq

3 , A1, A2, A3 A4 DPVBi EL, A5 DPVBi, DPVBi [12] DPVBi, Alq. NPB, EL,, NPB [13] DPVBi [5] ; [11,14 16] EL. DPVBi 50 nm, EL.,,.. OLED, (Al ), (1). So [11],, NPB/Alq EL Alq,.., Al. Al,,. NPB/DPVBi, (1), Al ( ) 2 DPVBi PL DPVBi EL,. OLED OLED [15,16],,,. ( ),, : 2n i d i cos θ 0 λ 2π (φ 1(λ)+φ 2 (λ)) = kλ, (1) i λ, n i d i i, θ 0, φ 1 (λ) φ 2 (λ), k. OLED. OLED [11],, (non-lambertian)., ΔL =2n DPVBi d DPVBi +2n Alq d Alq λ φ(λ), (2) 2π n DPVBi d DPVBi DPVBi, n Alq d Alq Alq, φ(λ) Al. (2),. DPVBi, (2).,, DPVBi 10 nm 40 nm, EL, DPVBi 50 nm, EL, DPVBi 10 nm 40 nm, ΔL ; DPVBi 50 nm, ΔL (EL ),. 2 DPVBi 50 nm EL ( ) DPVBi., 425 nm (DPVBi PL ), Alq [11] n Alq =1.75, φ(λ) =0, DPVBi n DPVBi =

4 ,., DPVBi,,.., DPVBi., EL., DPVBi 10 nm 20 nm, 234 cd/m cd/m 2 82%, ; DPVBi 30 nm, 426 cd/m cd/m 2, 50%; DPVBi 40 nm, 676 cd/m 2, 6%, DPVBi 50 nm, 633 cd/m 2. DPVBi 50 nm, DPVBi 50 nm, EL ( ),., DPVBi 40 nm,, 800 ma/cm cd/m 2. 1 DPVBi 20 ma/cm 2 A1 A2 A3 A4 A5 DPVBi /nm /V /(cd/m 2 ) /(cd/a) /V DPVBi - (a) - (b) 3 DPVBi - (a) - (b). DPVBi nm, DPVBi,, DPVBi, DPVBi 30 nm, 40 nm. 20 ma/cm 2, DPVBi 10 nm, 20 nm, 30 nm, 40 nm 50 nm A1, A2, A3, A4 A5 1. DPVBi nm, 10 nm, 0.8 V. DPVBi, DPVBi nm DPVBi :, DPVBi [12], NPB/DPVBi, DPVBi, [17], NPB/DPVBi. DPVBi, NPB/DPVBi Alq, Alq 6nm, [6,17], ( Alq ),.,,. DPVBi 10 nm 20 nm 20 nm 30 nm, 82% 50%, 30 nm 40 nm, 6%, NPB/DPVBi

5 30 nm,,, NPB/DPVBi 30 nm.,, DPVBi 30 nm. DPVBi 20 nm 30 nm, 50%, 20 nm., DPVBi nm. Alq : Tang [17] Alq Alq 5nm Alq 20 nm ; Kalinowski [18] Alq 30 ± 15nm.,. DPVBi nm,. 4 DPVBi - 1, DPVBi, DPVBi.. OLED, /,,,. /,,. DPVBi [5] 3.1 ev, DPVBi 50 nm A5 DPVBi, DPVBi nm A1, A2, A3 A4 DPVBi, DPVBi A1 2.8 V, DPVBi 3.1 ev. / LiBq [9] 4 MoO [7,8] 3,,, DPVBi ( ).,,,. 4., OLED,,, ma/cm 2,DPVBi 10 nm, 20 nm, 30 nm, 40 nm 50 nm 1., DPVBi 40 nm A4, 3.4 cd/a, DPVBi., 3.4cd/A 2.5%, [5] DPVBi ( 2.4%@8.28 ma/cm 2 ),,. A4 100 ma/cm 2, 3cd/A, 4.3 cd/a(@0.02 ma/cm 2 ), 3.2%.. 4 DPVBi, DPVBi DPVBi 40 nm, 3.4 V, 3.2%, cd/m 2, (0.15, 0.15). DPVBi 40 nm EL

6 DPVBi DPVBi nm.. [1] Zhou Y C, Zhou J, Zhao J M, Zhang S T, Zhan Y Q, Wang X Z, Wu Y, Ding X M, Hou X Y 2006 Appl. Phys. A [2] Jiao B, Wu Z X, Yan X W, Hou X 2010 Appl. Phys. A [3] Yap C C, Yahaya M, Salleh M M 2008 Curr. Appl. Phys [4] Xie W F, Hou J Y, Liu S Y 2003 Semicond. Sci. Technol. 18 L42 [5] Hosokawa C, Higashi H, Nakamura H, Kusumoto T 1995 Appl. Phys. Lett [6] Wu Y Z, Zheng X Y, Zhu W Q, Zhang B X, Jiang X Y, Zhang Z L, Xu S H 2002 Semiconductor Optoelectronics (in Chinese) [,,,,,, ] [7] Cao J, Jiang X Y, Zhang Z L 2006 Appl. Phys. Lett [8] Matsushima T, Kinoshita Y, Murata H 2007 Appl. Phys. Lett [9] Zhang Y, Li Y, Duan L, Zhang D Q, Qiu Y 2007 Acta Phys. Chim. Sin (in Chinese) [,,,, ] [10] Gebler D D, Wang Y Z, Blatchford J W, Jessen S W, Fu D K, Swager T M, MacDiarmid A G, Epstein A J 1997 Appl. Phys. Lett [11] So S K, Choi W K, Leung L M, Neyts K 1999 Appl. Phys. Lett [12] Jiang W L, Wang J, Ding G Y, Wang J, Wang L Z, Han Q, Liu S Y 2006 Chi. J. Lum (in Chinese) [,,,,,, ] [13] Tse S C, Kwok K C, So S K 2006 Appl. Phys. Lett [14] Lin C L, Lin H W, Wu C C 2006 Appl. Phys. Lett [15] Dodabalapur A, Rothberg L J, Jordan R H, Miller T M, Slusher R E, Phillips J M 1996 J. Appl. Phys [16] Chen S F, Deng L L, Xie J, Peng L, Xie L H, Fan Q L, Huang W 2010 Adv. Mater [17] Tang C W, Van Slyke S A, Chen C H 1989 J. Appl. Phys [18] Kalinowski J, Fattori V, Marco P D 2001 Chem. Phys

7 Influence of active layer thickness on the performance of distyrylarylene derivative blue organic light-emitting device Wu You-Zhi 1) Zhang Wen-Lin 1) Ni Wei-De 1) Zhang Cai-Rong 2) Zhang Ding-Jun 1 1) ( State Key Laboratory of Gansu Advanced Non-ferrous Metal Materials, School of Materials Science & Engineering, Lanzhou University of Technology, Lanzhou , China ) 2) ( Department of Applied Physics, School of Science, Lanzhou University of Technology, Lanzhou , China ) ( Received 12 August 2011; revised manuscript received 6 October 2011 ) Abstract Thickness of emissive layer in organic electroluminescent device is one of the important factors affecting the device performance. In this report, a blue electroluminescent device with an active layer of 4, 4 -bis(2, 2 -diphenylvinyl) -1, 1 - biphenyl (DPVBi) is fabricated. The device performance varies with the thickness of DPVBi. With the increase of the DPVBi thickness between nm, the device luminance and efficiency at the same current density first increase and then decrease, the device with a DPVBi thickness of 40 nm exhibits the highest luminance of cd/m 2 and a maximum external quantum efficiency of 3.2%, with Commission Internationale de l Eclairage (CIE) co-ordinates being (0.15, 0.15). The luminescent spectral red shift and the color purity deteriorate when the thickness is over 40 nm, which can be attributed to a result of microcavity effect. In the meantime, the analysis from experimental results shows that the exciton diffusion length in DPVBi is between nm. Keywords: luminescence, organic electroluminescence, blue, electroluminescent efficiency PACS: Fb, Le, Fi * Project supported by the Natural Science Foundation of Gansu Province, China (Grant No. 1010RJZA035), the Scientific Research Foundation for the Returned Overseas Chinese Scholars, State Education Ministry (Grant No. 40), and the National Natural Science Foundation of China (Grant Nos , ). youzhiwu@163.com