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首页> 外文学位 >Interfacial electron transfer (ET) from sensitizer/dyes to semiconductor nanocrystalline thin films studied by ultrafast infrared spectroscopy.
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Interfacial electron transfer (ET) from sensitizer/dyes to semiconductor nanocrystalline thin films studied by ultrafast infrared spectroscopy.

机译：超敏红外光谱研究了从敏化剂/染料到半导体纳米晶体薄膜的界面电子转移（ET）。

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Motivated by both applied and fundamental interests, interfacial electron transfer (ET) dynamics from molecular and polymeric adsorbates to inorganic semiconductor (SC) nanocrystalline thin films have been investigated by ultrafast transient absorption spectroscopy. In molecular systems, injection rate as a function of semiconductor matrix and bridge distance between donor and acceptor was examined by choosing proper dyes and semiconductors. For the polymeric composites, investigation focuses on two types of conjugated polymers, polyphenylenevinylene and polythiophene derivatives.; ET dynamics from Ru complexes to ZnO, Nb2O5 and SnO2 films were investigated and compared with the previous study on TiO2. All injection kinetics are shown to be biphasic, with ultrafast (100 fs) and slow (on ps or longer timescale) components, corresponding to injection from unthermalized and thermalized excited states of dye molecules respectively. A much faster injection rate from unthermalized excited states is observed for d-type semiconductor (Nb2O5 and TiO 2) than that for s-type semiconductor (ZnO and SnO2) likely due to orders of magnitude higher density of states in the former.; ET rate in the short-bridge limit as a function of methylene and phenyl bridge length was measured by testing ReCnA (n = 1--5) and RuPn (n = 0--2) dyes, respectively. The injection rate of ReCnA/SnO2 exhibited an exponential dependence on bridge length for n = 3--5 with a decay constant (beta) of 1.0/CH2. Deviation from the exponential dependence was observed for n = 1 and 2. The transfer rate from RuPn series to SnO2 films decays exponentially as a function of spacer length with beta of 0.3 A-1 at pH 2 and 0.44 A -1 on dry film.; Photoinduced electron injection dynamics from the conjugated polymers were studied as well. The ET from MEH-PPV to SnO2 and TiO 2 was found to occur within timescales of 800 and 100 fs; the faster injection rate to TiO2 is also attributed to orders of magnitude higher accepting density of states in TiO2 than in SnO2. The injection from polythiophenes to SnO2 occurs on 140 fs timescale, faster than that of MEH-PPV/SnO2, probably due to stronger binding in polythiophene with SnO2.
机译：受应用和基本兴趣的驱使，已经通过超快瞬态吸收光谱研究了从分子和聚合物吸附物到无机半导体（SC）纳米晶体薄膜的界面电子转移（ET）动力学。在分子系统中，通过选择合适的染料和半导体来检查注入速率与半导体基质的关系以及供体与受体之间的桥距离。对于聚合物复合材料，研究集中在两种共轭聚合物上，聚苯撑亚乙烯基和聚噻吩衍生物。研究了Ru配合物对ZnO，Nb2O5和SnO2薄膜的ET动力学，并将其与先前的TiO2研究进行了比较。所有注入动力学都显示为双相的，具有超快（<100 fs）和慢速（以ps或更长的时间标度）组成，分别对应于从染料分子的未加热和热化激发态注入。 d型半导体（Nb2O5和TiO 2）的未热激发态注入速率比s型半导体（ZnO和SnO2）要快得多，这可能是由于前者的态密度较高。通过分别测试ReCnA（n = 1--5）和RuPn（n = 0--2）染料来测量短桥限中ET速率与亚甲基和苯基桥长的关系。在n = 3--5时，ReCnA / SnO2的注入速率与桥长呈指数关系，衰减常数（β）为1.0 / CH2。对于n = 1和2，观察到与指数依赖性的偏差。从RuPn系列到SnO2薄膜的转移速率随间隔物长度的变化呈指数衰减，其中在pH 2时β为0.3 A-1，而在干膜上为0.44 A -1。 ;还研究了来自共轭聚合物的光诱导电子注入动力学。发现从MEH-PPV到SnO2和TiO 2的ET发生在800和<100 fs的时间范围内。 TiO 2的更快注入速率还归因于TiO 2中的状态接受密度比SnO 2中高几个数量级。从聚噻吩向SnO2的注入发生在140 fs的时标上，比MEH-PPV / SnO2的注入速度更快，这可能是由于聚噻吩与SnO2的结合更强。

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