物理学报
物理學報
물이학보
2013年
6期
369-377
,共9页
薛振杰%李葵英?%孙振平
薛振傑%李葵英?%孫振平
설진걸%리규영?%손진평
硒化镉量子点%光生载流子%表面光电压谱%表面光声光谱
硒化鎘量子點%光生載流子%錶麵光電壓譜%錶麵光聲光譜
서화력양자점%광생재류자%표면광전압보%표면광성광보
CdSe quantum dots%photo-generated carriers%surface photovoltage spectroscopy%surface photoacous-tic spectroscopy
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.
採用水溶液法閤成瞭巰基乙痠(TGA)包覆的CdSe量子點.通過X射線粉末衍射和高分辨透射顯微鏡檢測結果證實,閤成得到閃鋅礦結構CdSe量子點.能譜圖和傅裏葉變換紅外光譜圖結果說明,在覈CdSe納米粒子錶麵與配體TGA之間有CdS殼層結構形成.利用樣品錶麵光電壓(SPV)譜,指認CdSe量子點精細能帶結構以及各自對應的激髮態特徵:475 nm (2.61 eV)和400 nm (3.1 eV)兩箇波長處的SPV響應峰分彆與CdSe覈和CdS殼層帶-帶隙躍遷相對應;370 nm (3.35 eV)附近SPV響應峰可能與TGA中羰基與巰基或羧基之間髮生的n→π?躍遷有關.場誘導錶麵光電壓譜結果證實,閤成的CdSe量子點具有明顯的N型錶麵光伏特性,而上述n→π?躍遷則具有P型錶麵光伏特性.熒光光譜譜線均勻增寬以及SPV響應峰位藍移,說明樣品具有明顯的量子呎吋效應.結閤不同pH值下閤成的CdSe量子點的SPV譜和錶麵光聲譜髮現, SPV響應彊度與錶麵光聲光譜信號彊度變化趨勢恰好相反.上述樣品錶麵光伏效應錶明, CdSe量子點錶麵和相界麵處的精細電子結構以及光生載流子的輸運特性均與量子點的呎吋大小存在某種內在聯繫.
채용수용액법합성료구기을산(TGA)포복적CdSe양자점.통과X사선분말연사화고분변투사현미경검측결과증실,합성득도섬자광결구CdSe양자점.능보도화부리협변환홍외광보도결과설명,재핵CdSe납미입자표면여배체TGA지간유CdS각층결구형성.이용양품표면광전압(SPV)보,지인CdSe양자점정세능대결구이급각자대응적격발태특정:475 nm (2.61 eV)화400 nm (3.1 eV)량개파장처적SPV향응봉분별여CdSe핵화CdS각층대-대극약천상대응;370 nm (3.35 eV)부근SPV향응봉가능여TGA중탄기여구기혹최기지간발생적n→π?약천유관.장유도표면광전압보결과증실,합성적CdSe양자점구유명현적N형표면광복특성,이상술n→π?약천칙구유P형표면광복특성.형광광보보선균균증관이급SPV향응봉위람이,설명양품구유명현적양자척촌효응.결합불동pH치하합성적CdSe양자점적SPV보화표면광성보발현, SPV향응강도여표면광성광보신호강도변화추세흡호상반.상술양품표면광복효응표명, CdSe양자점표면화상계면처적정세전자결구이급광생재류자적수운특성균여양자점적척촌대소존재모충내재련계.
@@@@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.
