共查询到19条相似文献,搜索用时 125 毫秒
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多孔硅中两种不同的光致发光谱 总被引:5,自引:2,他引:3
采用连续变化的单色光作为激发光源,测量了多孔硅的光致发光(PL)谱和光致发光激发(LPE)谱.结果表明,多孔硅存在两种不同的PL谱.一种是人们通常观察到的PL谱,其峰位可随多孔硅量子尺寸的变小以及激发光波长(λex)的变短而蓝移,我们称其力量子限制型光致发光(QPL)谱.另一种是其峰位波长处于蓝紫光范围且峰位基本上不随多孔硅的量子尺寸和λex而变化的PL谱,我们称其为非量子限制型光致发光(NQPL)谱.多孔硅还存在与PL谱相对应的两种不同的PLE谱.与QPL谱对应的PLE谱是双峰谱,与NQPL谱对应的PL 相似文献
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用于液晶盒偶氮染料光致取向层的合成和性质 总被引:1,自引:0,他引:1
我们研究了可用于光致取向液晶(LCs)偶氮染料的合成和性质,提出了偶氮染料的结构与合成过程。偶氮染料光致取向完全是因为分子吸收振子垂直于UV光偏振方向的再取向。讨论了在偏振光场中,偶氮染料分子旋转扩散现象的定性模型。测量了波长为372nm时,偏振吸收光谱的有序参数S=-0.4(80%的最大绝对值Sm=-0.5)。对一个偶氮染料膜,利用在正常的正入射偏振光之后,紧跟一个斜入射的非偏振光两步曝光,可以获得温度稳定的5.3°预倾角。光致取向基片的方位角锚定能为Aφ≈10-4Jm-2,这与摩擦聚酰亚胺(PI)层的锚定能相同。我们发现,光致取向液晶盒的电压保持率甚至比摩擦PI层取向的还高,因此,偶氮染料完全可以用作有源矩阵液晶显示器的取向层。光致取向偶氮染料层的热稳定性很高,但UV稳定性需通过诸如聚合等来改良。于是,我们设想了一种新的基于聚合偶氮染料层的LCD取向技术。 相似文献
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在激光辐照或退火作用下 ,As2 S3非晶半导体薄膜的光学吸收边出现红移现象 ,并且随着激光功率的增大和辐照时间的延长 ,红移值增大 ,并最后达到饱和。这种红移在先经过退火处理再激光辐照的薄膜中是可逆的。从扫描电镜的形貌图中也可以看出 ,经激光辐照后 ,薄膜表面有晶相出现 ,且随着激光功率的增加 ,晶相出现增多。As2 S3非晶半导体薄膜中光致效应的产生是由于光致结构变化所致 ,对其产生原因 ,进行了机理分析 相似文献
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偶氮染料光致异构过程的研究 总被引:1,自引:0,他引:1
组建了偶氮染料的光致变色测试系统.进而用该系统研究了甲基红(MR)溶液和MR/聚甲基丙烯酸甲酯(PMMA)薄膜的光致异构过程。结果表明:增大激发光的光强与延长激发时间对促进MR分子光致异构具有等效作用。而且MR分子的光致异构过程对周围的空间位阻有很强的依赖性;偶氮分子因光致异构引起的光致变色实质上有光致异构为主的快过程和偶氮分子沿激光偏振方向取向为主的慢过程,取向状态在偶氮染料掺杂聚合物薄膜中可以长时间地保持。 相似文献
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分别采用紫外光和He—Cd激光辐照,实验研究了As2S8非晶态薄膜的光致折射率变化以及膜厚变 化的现象,归纳了实验规律,初步分析了机理。利用光诱起折射率变化效应试制了As2S8玻璃条波导,实现了良好 的导波特性。 相似文献
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分别采用紫外光和He-Cd激光辐照,实验研究了As2S8非晶态薄膜的光致折射率变化以及膜厚变化的现象,归纳了实验规律,初步分析了机理。利用光诱起折射率变化效应试制了As2S8玻璃条波导,实现了良好的导波特性。 相似文献
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偶氮液晶聚合物(LCP)是一种新型的光存储材料。本文介绍了偶氮LCP中的双光子光致双折射效应,提出了基于偏振角度复用法在偶氮LCP中进行多灰阶存储的基本原理,方法和技术,给出了灰阶存储的原理性实验结果,设计了偶氮LCP灰阶存储器的光学系统结构方案。 相似文献
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Dmitri Godovsky Lichun Chen Leif Pettersson Olle Ingans Mats R. Andersson Jan C. Hummelen 《Advanced functional materials》2000,10(2):47-54
We use a combinatorial approach to develop molecular plastic solar cells based on soluble fullerene derivatives blended with conjugated polymers. A combinatorial way of sample preparation is well suited to deal with the multitude of possible combinations of the components of such blends. We use high mobility poly(thiophene) and poly(phenylenevinylene) derivatives to be combined with acceptors. Gradients of methanofullerene/polymer concentration were formed by diffusion of the low molecular weight component in the spin‐cast polymer matrix. Likewise the gradients of zinc phthalocyanine/C60 were prepared by co‐evaporation of the two materials from two sources to make a linear array of photodiode devices. Photo‐ and electrophysical properties, such as absorption, luminescence, short circuit photocurrent and open circuit photovoltage, were measured using a specially designed installation with a resolution of 70–100 µ. Clear evidence was obtained that the photoconversion efficiency increased with the amount of methanofullerene up to very high levels, in the case of methanofullerene/polymer blends, verifying the important role of the acceptor in the photoconversion. By choosing the optimal ratio between C60 and ZnPc in the evaporated layer it is possible to obtain high photocurrent in the 600–700 nm range, due to the added contribution from photoinduced electron transfer between the two molecules. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
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Optical,Electrical, and Magnetic Studies of Organic Solar Cells Based on Low Bandgap Copolymer with Spin ½ Radical Additives 下载免费PDF全文
Tek Basel Uyen Huynh Tianyue Zheng Tao Xu Luping Yu Z. Valy Vardeny 《Advanced functional materials》2015,25(12):1895-1902
The charge photogeneration and recombination processes in organic photovoltaic solar cells based on blend of the low bandgap copolymer, PTB7 (fluorinated poly‐thienothiophene‐benzodithiophene) with C60‐PCBM using optical, electrical, and magnetic measurements in thin films and devices is studied. A variety of steady state optical and magneto‐optical techniques were employed, such as photoinduced absorption (PA), magneto‐PA, doping‐induced absorption, and PA‐detected magnetic resonance (PADMR); as well as picosecond time‐resolved PA. The charge polarons and triplet exciton dynamics in films of pristine PTB7, PTB7/fullerene donor–acceptor (D–A) blend is followed. It is found that a major loss mechanism that limits the power conversion efficiency (PCE) of PTB7‐based solar cell devices is the “back reaction” that leads to triplet exciton formation in the polymer donor from the photogenerated charge‐transfer excitons at the D–A interfaces. A method of suppressing this “back reaction” by adding spin½ radicals Galvinoxyl to the D–A blend is presented; this enhances the cell PCE by ≈30%. The same method is not effective for cells based on PTB7/C70‐PCBM blend, where high PCE is reached even without Galvinoxyl radical additives. 相似文献
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制备了具有不同偶氮生色团掺杂浓度的主客式聚甲基丙烯酸甲酯(PMMA)样品。利用介电测量的方法,观测了样品在532nm光照射下的介电常数和介电损耗的变化。发现随着生色团浓度的增加,样品的介电常数增大;而生色团的掺人对于聚甲基丙烯酸甲酯样品的介电损耗则主要表现在对β弛豫的影响。浓度一定的生色团样品的介电常数随着激发光功率的增加而增大;样品的高频介电损耗随着激发光功率的增大而减小,但低频直流电导损耗则随着激发光功率的增加而增大。利用生色团在光致异构反应和取向运动过程中与聚甲基丙烯酸甲酯基体的相互作用,定性地解释了上述实验现象。 相似文献
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用5,5′-(六氟异丙基)-二-(2-氨基苯酚)(6FHP)、均苯四甲酸酐(PMDA)及分散红1(DR1)合成了具有光致变色性能的含偶氮苯侧链型聚酰亚胺。利用红外(IR)、紫外-可见(UV-Vis)、示差扫描量热(DSC)和热失重分析(TGA)等手段对该光致变色聚合物材料进行了结构和热性能表征。示差扫描量热分析测得其玻璃化转变温度为298℃,热重分析测得其热分解温度为365℃,表明具有非常好的热稳定性。研究了该材料的N-甲基-2-吡咯烷酮(NMP)溶液和聚合物薄膜在紫外光诱导下的光异构化及热回复异构化行为。结果表明,在一定波长(365 nm)紫外光诱导下均能发生光致变色现象,对于实现偶氮材料的永久光致双折射和永久光存储具有一定意义。 相似文献
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L. Rossi G. Bongiovanni G. Lanzani A. Mura A. Borghesi R. Tubino J. Kalinowski 《Advanced functional materials》1997,7(1):35-38
We have studied the photophysics of linear trans-quinacridone films by applying a variety of transient and continuous wave photomodulation techniques. Our experimental results demonstrate the ultrafast formation of excimer species which are responsible for the emission. The excimer decay kinetics seems to suggest a predominantly charge transfer character of these emitting species. This is consistent with the long-lived states which we detected on the millisecond time scale. © 1997 John Wiley & Sons, Ltd. 相似文献