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采用水溶液法合成了巯基乙酸(TGA) 包覆的CdSe 量子点. 通过X 射线粉末衍射和高分辨透射显微镜检测结果证实, 合成得到闪锌矿结构CdSe 量子点. 能谱图和傅里叶变换红外光谱图结果说明, 在核CdSe 纳米粒子表面与配体TGA 之间有CdS 壳层结构形成. 利用样品表面光电压(SPV) 谱, 指认CdSe 量子点精细能带结构以及各自对应的激发态特征: 475 nm (2.61 eV) 和400 nm (3.1 eV) 两个波长处的SPV 响应峰分别与CdSe 核和CdS 壳层带-带隙跃迁相对应; 370 nm (3.35 eV) 附近SPV 响应峰可能与TGA 中羰基与巯基或羧基之间发生的n →π* 跃迁有关. 场诱导表面光电压谱结果证实, 合成的CdSe 量子点具有明显的N 型表面光伏特性, 而上述n→π* 跃迁则具有P 型表面光伏特性. 荧光光谱谱线均匀增宽以及SPV 响应峰位蓝移, 说明样品具有明显的量子尺寸效应. 结合不同pH 值下合成的CdSe 量子点的SPV 谱和表面光声谱发现, SPV 响应强度与表面光声光谱信号强度变化趋势恰好相反. 上述样品表面光伏效应表明, CdSe 量子点表面和相界面处的精细电子结构以及光生载流子的输运特性均与量子点的尺寸大小存在某种内在联系.In the present paper, we synthesize CdSe quantum dots (QDs) that are stabilized by thioglycolic acid according to the water-phase synthesis. The X-ray diffraction and HRTEM results confirm that the samples prepared each possess a sphalerite structure. The EDS and FT-IR spectra of the samples show that a core-shell structure is formed between the CdSe nanoparticles and the ligand. The fine band structures and the characteristics of the surface states in a connection with the structures are identified by the surface photovoltage (SPV) spectrum of the samples. Two SPV response peaks, located at 475 nm (2.61 eV) and 400 nm (3.1 eV), are closely related to the band-band transitions of the core-CdSe and the shell-CdS, respectively; the SPV response at 370 nm (3.35 eV) is correlated with the n → π* transition between the hydroxyl and sulfydryl (or hydroxyl). It is because of an obvious quantum size effect of the samples that both PL line broadens and SPV response intensity increases with the decrease of the grain size of the sample. The change trend of the surface photoacoustic signal intensity is contrary to that of the SPV response intensity of the samples synthesized at varying pH. Moreover, the fine band structures at surfaces and grain boundaries of CdSe QDs prepared are probed by the SPV spectra of the samples at varying pH values. The relationship between the grain size and the photo-generated carrier transport behavior is discussed according to the detected EFISPV results of the QDs.
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Keywords:
- CdSe quantum dots /
- photo-generated carriers /
- surface photovoltage spectroscopy /
- surface photoacoustic spectroscopy
[1] Xu X Q, Sixto G, Iván M S, Antonio A, Juan B, Xu G 2010 Mater. Chem. Phys. 124 709
[2] Yang Z S, Chem C Y, Roy P, Chang H T 2011 Chem. Commun. 47 9561
[3] Qu D L, Zhang Z S, Yue S Z, Wu Q Y, Yan P R, Zhao Y, Liu S Y 2012 Chin. Phys. Lett. 29 097805
[4] Vibin M, Vinayakan R, John A, Rejiya C S, Raji V, Abraham A 2011 J. Colloid Interface Sci. 357 366
[5] Huang H B, Xu L, Chen H M, Huang X F, Chen K J, Feng D 1999 Chin. Phys. 8 40
[6] Peng Z A, Peng J 2001 J. Am. Chem. Soc. 123 183
[7] Miao Y M, Li C R, Cao L, Liu R B, He Y P, Xie S S, Zou B S 2005 Chin. Phys. 14 2262
[8] Li L Q, Liu A P, Zhao H X, Cui C, Tang W H 2012 Acta Phys. Sin. 61 108201 (in Chinese) [李立群, 刘爱萍, 赵海新, 崔灿, 唐为华 2012 61 108201]
[9] Mahmoud W E, Al-Amri A M, Yaghmour S J 2012 Opt. Mater. 34 1082
[10] Wang Y L, Mo Y C, Zhou L Y 2011 Spectrochim. Acta A 79 1311
[11] Kim S M, Yang H S 2011 Curr. Appl. Phys. 11 1056
[12] Chen D A, Shen L, Zhang J Y, Cui Y P 2007 Acta Phys. Sin. 56 6340 (in Chinese) [陈定安, 沈 里, 张家雨, 崔一平 2007 56 6340]
[13] Liu B C, Pan X Q, Tian Q, Wu Z L 2006 Chin. Phys. 15 1067
[14] Woggon U, Gindele F, Wind O, Klingshirn C 1996 Phys. Rev. B 54 1506
[15] Li K Y, Song G J, Zhang J, Wang C M, Guo B 2011 J. Photochem. Photobiol. A 218 213
[16] Li K Y, Zhang H, Yang W Y, Wei S L, Wang D Y 2010 Mater. Chem. Phys. 123 98
[17] Klayman D L, Griffin T S 1973 J. Am. Chem. Soc. 95 197
[18] Kronik L, Shapira Y 1999 Surf. Sci. Rep. 37 24
[19] Yu W W, Qu L H, Guo W Z, Peng X 2003 Chem. Mater. 15 2854
[20] Fang R C 2001 Solid State Spectroscopy (Hefei: University of Science and Technology of China Press) pp177-180 (in Chinese) [方容川 2001固体光谱学 (合肥: 中国科学技术大学出版社) 第177–180页]
[21] Sadao A (Translated by Ji Z G et al.) 2009 Properties of Group-IV, III-V and II-VI Semiconductors (Beijing: Sciecne Press) p144, 161, 209 (in Chinese) [Sadao A (季振国等译) 2009 IV族, III-V族和II-VI族半导体材料的特性 (北京: 科学出版社) 第144, 161, 209页]
[22] Woggon U 1998 Optical Properties of Semiconductor Quantum Dots (Berlin: Springer-Verlag) pp52-62
[23] Yang W Y, Li K Y, Wei S L, Song G J, Zhang J 2011 11th IUMRS International Conference in Asia Qingdao, China, September 25-28, 2010 p114
[24] Li M Z 2006 Technique and Applications of Spectral Analysis (Beijing: Science Press ) pp43-44 (in Chinese) [李民赞 2006光谱分析技术及其应用 (北京:科学出版社)第43–44页]
[25] Li K Y, Liu T, Zhou B J, Wei S L, Yang W Y 2010 Acta Phys. -Chem. Sin. 26 403 (in Chinese) [李葵英, 刘 通, 周冰晶, 魏赛玲, 杨伟勇 2010 物理化学学报 26 403]
[26] Huang K 1985 Solid State Physics (Beijing: Higher Education Press) pp354-355 (in Chinese) [黄 昆 1985固体物理学 (北京: 高等教育出版社) 第354-355页]
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[1] Xu X Q, Sixto G, Iván M S, Antonio A, Juan B, Xu G 2010 Mater. Chem. Phys. 124 709
[2] Yang Z S, Chem C Y, Roy P, Chang H T 2011 Chem. Commun. 47 9561
[3] Qu D L, Zhang Z S, Yue S Z, Wu Q Y, Yan P R, Zhao Y, Liu S Y 2012 Chin. Phys. Lett. 29 097805
[4] Vibin M, Vinayakan R, John A, Rejiya C S, Raji V, Abraham A 2011 J. Colloid Interface Sci. 357 366
[5] Huang H B, Xu L, Chen H M, Huang X F, Chen K J, Feng D 1999 Chin. Phys. 8 40
[6] Peng Z A, Peng J 2001 J. Am. Chem. Soc. 123 183
[7] Miao Y M, Li C R, Cao L, Liu R B, He Y P, Xie S S, Zou B S 2005 Chin. Phys. 14 2262
[8] Li L Q, Liu A P, Zhao H X, Cui C, Tang W H 2012 Acta Phys. Sin. 61 108201 (in Chinese) [李立群, 刘爱萍, 赵海新, 崔灿, 唐为华 2012 61 108201]
[9] Mahmoud W E, Al-Amri A M, Yaghmour S J 2012 Opt. Mater. 34 1082
[10] Wang Y L, Mo Y C, Zhou L Y 2011 Spectrochim. Acta A 79 1311
[11] Kim S M, Yang H S 2011 Curr. Appl. Phys. 11 1056
[12] Chen D A, Shen L, Zhang J Y, Cui Y P 2007 Acta Phys. Sin. 56 6340 (in Chinese) [陈定安, 沈 里, 张家雨, 崔一平 2007 56 6340]
[13] Liu B C, Pan X Q, Tian Q, Wu Z L 2006 Chin. Phys. 15 1067
[14] Woggon U, Gindele F, Wind O, Klingshirn C 1996 Phys. Rev. B 54 1506
[15] Li K Y, Song G J, Zhang J, Wang C M, Guo B 2011 J. Photochem. Photobiol. A 218 213
[16] Li K Y, Zhang H, Yang W Y, Wei S L, Wang D Y 2010 Mater. Chem. Phys. 123 98
[17] Klayman D L, Griffin T S 1973 J. Am. Chem. Soc. 95 197
[18] Kronik L, Shapira Y 1999 Surf. Sci. Rep. 37 24
[19] Yu W W, Qu L H, Guo W Z, Peng X 2003 Chem. Mater. 15 2854
[20] Fang R C 2001 Solid State Spectroscopy (Hefei: University of Science and Technology of China Press) pp177-180 (in Chinese) [方容川 2001固体光谱学 (合肥: 中国科学技术大学出版社) 第177–180页]
[21] Sadao A (Translated by Ji Z G et al.) 2009 Properties of Group-IV, III-V and II-VI Semiconductors (Beijing: Sciecne Press) p144, 161, 209 (in Chinese) [Sadao A (季振国等译) 2009 IV族, III-V族和II-VI族半导体材料的特性 (北京: 科学出版社) 第144, 161, 209页]
[22] Woggon U 1998 Optical Properties of Semiconductor Quantum Dots (Berlin: Springer-Verlag) pp52-62
[23] Yang W Y, Li K Y, Wei S L, Song G J, Zhang J 2011 11th IUMRS International Conference in Asia Qingdao, China, September 25-28, 2010 p114
[24] Li M Z 2006 Technique and Applications of Spectral Analysis (Beijing: Science Press ) pp43-44 (in Chinese) [李民赞 2006光谱分析技术及其应用 (北京:科学出版社)第43–44页]
[25] Li K Y, Liu T, Zhou B J, Wei S L, Yang W Y 2010 Acta Phys. -Chem. Sin. 26 403 (in Chinese) [李葵英, 刘 通, 周冰晶, 魏赛玲, 杨伟勇 2010 物理化学学报 26 403]
[26] Huang K 1985 Solid State Physics (Beijing: Higher Education Press) pp354-355 (in Chinese) [黄 昆 1985固体物理学 (北京: 高等教育出版社) 第354-355页]
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