CAJ | 학술논문

半导体量子点（QDs）具有发光效率高和发光波长可调等特点。采用胶体CdSe QDs作电致发光器件的有源材料，TPD（N ，N′-biphenyl-N ，N′-bis-（3-methylphenyl）-1，1′-biphenyl-4，4′-diamine）作空穴传输层， ZnS作电子传输层，研究了有机/无机复合发光器件ITO/TPD/CdSe QDs/ZnS/Ag的电致发光特性。TPD和CdSe QDs薄膜采用旋涂方法、ZnS薄膜采用磁控溅射方法沉积，器件表面平整。CdSe QDs的光致发光和电致发光谱峰位波长均位于～580 nm ，属于量子点的带边激子发光。我们与以前的ITO/ZnS/CdSe QDs/ZnS/Ag发光器件结构进行了对比，发现新的器件结构的电致发光谱没有观察到QDs表面态的发光，而且新器件的发光强度是ITO/ZnS/CdSe QDs/ZnS/Ag结构的～10倍。发光效率的提高归因于碰撞激发与载流子注入两种发光机制并存的结果：一方面电子经过ZnS 层加速后，碰撞激发CdSe QDs发光；另一方面，空穴从T PD层注入CdSe QDs与QDs中激发的电子复合发光。我们进一步研究了ZnS电子加速层厚度对发光特性的影响，选择ZnS薄膜的厚度分别是80，120和160 nm ，发现随着ZnS层厚度增大，器件启亮电压升高， EL强度增大，但是击穿电压降低。EL峰位随着ZnS厚度的减小发生明显蓝移，对上述实验现象进行了机理解释。
반도체양자점（QDs）구유발광효솔고화발광파장가조등특점。채용효체CdSe QDs작전치발광기건적유원재료，TPD（N ，N′-biphenyl-N ，N′-bis-（3-methylphenyl）-1，1′-biphenyl-4，4′-diamine）작공혈전수층， ZnS작전자전수층，연구료유궤/무궤복합발광기건ITO/TPD/CdSe QDs/ZnS/Ag적전치발광특성。TPD화CdSe QDs박막채용선도방법、ZnS박막채용자공천사방법침적，기건표면평정。CdSe QDs적광치발광화전치발광보봉위파장균위우～580 nm ，속우양자점적대변격자발광。아문여이전적ITO/ZnS/CdSe QDs/ZnS/Ag발광기건결구진행료대비，발현신적기건결구적전치발광보몰유관찰도QDs표면태적발광，이차신기건적발광강도시ITO/ZnS/CdSe QDs/ZnS/Ag결구적～10배。발광효솔적제고귀인우팽당격발여재류자주입량충발광궤제병존적결과：일방면전자경과ZnS 층가속후，팽당격발CdSe QDs발광；령일방면，공혈종T PD층주입CdSe QDs여QDs중격발적전자복합발광。아문진일보연구료ZnS전자가속층후도대발광특성적영향，선택ZnS박막적후도분별시80，120화160 nm ，발현수착ZnS층후도증대，기건계량전압승고， EL강도증대，단시격천전압강저。EL봉위수착ZnS후도적감소발생명현람이，대상술실험현상진행료궤리해석。
In the present paper ,to fabricate electroluminescent devices CdSe QDs were used as active materials ,TPD (N ,N′-bi-phenyl-N ,N′-bis-(3-methylphenyl)-1 ,1′-biphenyl-4 ,4′-diamine) was used as a hole transport layer ,and ZnS was used as an elec-tron transport layer .The electroluminescent properties of the organic/inorganic composite ITO/TPD/CdSe QDs/ZnS/Ag light emitting devices were studied .Both TPD and CdSe QDs thin films were spin-coated and ZnS thin films were deposited by magne-tron sputtering .The surfaces of the devices are smooth .The luminescence (EL) peak of the CdSe QDs is at 580 nm which is as-signed to the band-edge exciton emission .Compared to the previous EL device of ITO/ZnS/CdSe QDs/ZnS/Ag ,it is seen that the new devices do not display surface state related emission peaks and EL intensity is about 10 folds that of the previous device . The enhancement of luminescence efficiency is attributed to both of the excitation of CdSe QDs by accelerated electron collision and carriers injection into QDs :(1) electrons are accelerated by the ZnS layer and collide with CdSe QDs ,which excites electrons in QDs to excited states and allows them to emit photons ;(2) the holes injected into QDs recombine with some of electrons ex-cited in the QDs .The authors further studied the influence of thickness variation of ZnS on the luminescent properties .ZnS thin films are of 80 ,120 ,and 160 nm thickness ,respectively .It was found that as the thickness of ZnS increases the threshold volt-age rises and EL intensity increases ,but breakdown voltage decreases .The EL peak position blue shifts when the thickness of ZnS decreases .The explanation of underlying mechanism is given .