Highly photoactive chemically modified thin films of chloroaluminum (and bromoaluminum) phthalocyanines probed by NEXAFS and UPS: Determination of the electronic structure and the molecular orientation
Highly photoactive chemically modified thin films of chloroaluminum (and bromoaluminum) phthalocyanines probed by NEXAFS and UPS: Determination of the electronic structure and the molecular orientation
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通过 NEXAFS 和 UPS 探测氯铝（和溴铝）酞菁的高光活性化学改性薄膜：电子结构和分子取向的测定
DOI：
10.1021/j100154a049
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发表时间：
1991
期刊：
影响因子：
--
通讯作者：
R. Garrett
中科院分区：
文献类型：
--
作者：
D. Guay;G. Tourillon;L. Gastonguay;J. Dodelet;K. Nebesny;N. Armstrong;R. Garrett
用C和N K边的近边X射线吸收精细结构(NEXAFS)和可变激发能(2 1.2和12 0 eV)下的紫外光电子能谱(UPS)研究了在玻璃或SnO{sub2}衬底上沉积的经化学转化的氯铝酞菁(ClAlPc)薄膜的电子结构和分子取向.当薄膜在酸性水溶液中浸泡时，发生相变H，而在溶液中加入I{sub3}{sup{负}}/i{sup{负}}，则观察到相变I。结果表明，在这两种转变过程中，ClAlPc的氮杂氮原子都发生质子化。它改变了化合物的价带，但对材料的空置能级没有影响。除了质子化作用外，I{sub3}{sup{减去}}在转变I过程中的吸收导致了酞菁和碘物种之间形成电荷转移络合物，改变了材料的占据能级和未占据能级。对于H相和I相，禁带宽度分别减小了0.3 eV和1.5 eV。当氯铝酞菁沉积在SnO{sub2}上时，没有观察到与取向有关的效应。相反，在沉积在浮法玻璃衬底上的酞菁的NEXAFS光谱中观察到了强偏振效应。
Near edge x-ray absorption fine structure (NEXAFS) at the C and N K edges and UV photoelectron spectroscopy (UPS) at variable excitation energy (21.2 and 120 eV) have been used to characterize the electronic structure and the molecular orientation of chloroaluminum phthalocyanine (ClAlPc) thin films deposited on glass or SnO{sub 2} substrates and subjected to chemical transformations. Transformation H occurs when the films are soaked in an aqueous acidic solution, while transformation I is observed if I{sub 3}{sup {minus}}/I{sup {minus}} is added to the solution. It is demonstrated that the protonation of the aza nitrogen atoms of ClAlPc happens during both transformations. It modifies the valence band of the compound but has no effect on the unoccupied levels of the material. Besides the protonation, the uptake of I{sub 3}{sup {minus}} in the phthalocyanine film during transformation I leads to the formation of a charge-transfer complex between the phthalocyanine and the iodine species with a modification of both the occupied and unoccupied levels of the material. The band gap is reduced by 0.3 eV and 1.5 eV for transformations H and I, respectively. No orientation-dependent effect is observed when the chloroaluminum phthalocyanine is deposited on SnO{sub 2}. On the contrary, strongmore » polarization effects are observed in the NEXAFS spectra of phthalocyanine deposited on a float glass substrate.« less