Photoconductivity of nanocrystalline SnO₂sensitized with colloidal CdSe quantum dots

Abstract

A highly reproducible photoresponse is observed in nanocrystalline SnO 2 thick films sensitized with CdSe quantum dots. The effect of the SnO 2 matrix microstructure on the photoconductivity kinetics and photoresponse amplitude is demonstrated. The photoresponse of the sensitized SnO 2 thick films reaches more than two orders of magnitude under illumination with the wavelength of the excitonic transition of the quantum dots. Long-term photoconductivity kinetics and photoresponse dependence on illumination intensity reveal power-law behavior inherent to the disordered nature of SnO 2 . The photoconductivity of the samples rises with the coarsening of the granular structure of the SnO 2 matrix. At the saturation region, the photoresponse amplitude remains stable under 10 4 pulses of illumination switching, demonstrating a remarkably high stability.

Light-Activated Sub-ppm NO2 Detection by Hybrid ZnO/QD Nanomaterials vs. Charge Localization in Core-Shell QD

“…To prepare CdSe and CdS nanocrystals stabilized with oleic acid, a pre-synthesized anionic precursor tri-n-octylphosphine selenide (TOPSe) or tri-n-octylphosphine sulfide (TOPS) and a freshly prepared cationic precursor cadmium oleate were used (Vasiliev et al, 2013). To synthesize the anionic precursors 0.01 mole of ground selenium or sulfur were added to 10 ml of tri-n-octylphosphine (C 8 H 17 ) 3 P (TOP, 90% pure, Fluke).…”

“…However, for this it is necessary to shift the optical sensitivity of semiconductor oxides from the UV range to longer wavelengths. This can be achieved by creating the defects in the semiconductor matrix (Han et al, 2012(Han et al, , 2013Varechkina et al, 2012;Geng et al, 2013;Zhang et al, 2017) or using the sensitizers that absorb light in the visible range (Peng et al, 2011;Vasiliev et al, 2013;Chizhov et al, 2014Chizhov et al, , 2016Chizhov et al, , 2018Yang et al, 2014;Zhang et al, 2015;Geng et al, 2016a,b;Paolesse et al, 2017;Rumyantseva et al, 2018). In the latter case, the consistency between the energy levels of metal oxide and sensitizer, is the necessary condition ensuring the transfer possibility of photoexcited charge carriers from the sensitizer to the semiconductor matrix (Minami et al, 1998;Ivanov et al, 2007;Kim et al, 2009;Vasiliev et al, 2011;Mordvinova et al, 2014).…”

“…In the latter case, the consistency between the energy levels of metal oxide and sensitizer, is the necessary condition ensuring the transfer possibility of photoexcited charge carriers from the sensitizer to the semiconductor matrix (Minami et al, 1998;Ivanov et al, 2007;Kim et al, 2009;Vasiliev et al, 2011;Mordvinova et al, 2014). A II B VI and A III B V semiconductor quantum dots (QDs) (Vasiliev et al, 2013;Chizhov et al, 2014Chizhov et al, , 2016Chizhov et al, , 2018Yang et al, 2014;Geng et al, 2016a,b) and organic dyes (Peng et al, 2011;Zhang et al, 2015;Paolesse et al, 2017;Rumyantseva et al, 2018) are suitable visible light sensitizers for wide gap semiconductor metal oxides.…”

Модификация спектров фотопроводимости в композитных структурах ZnO-квантовые точки CdSe под действием дополнительного фотовозбуждения

“…Нанокристаллы CdSe размером 2.8 ± 0.2 нм синтезированы высокотемпературным коллоидным методом с использованием олеиновой кислоты в качестве стабилизатора [10] Размер квантовых точек определен из данных спектроскопии видимого поглощения по калибровке, приведенной в работе [11], и из данных просвечивающей электронной микроскопии (рис. 1, b).…”

Photosensitive Organic-Inorganic Hybrid Materials for Room Temperature Gas Sensor Applications

“…However, bulk wide-gap metal oxides are transparent in the visible range of the spectrum. Based on the published data [ 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 ] for shifting the wavelength range of optical sensitivity of transparent conductive oxides towards longer wavelengths, it is necessary to create defects in the semiconductor matrix [ 27 , 28 , 29 , 30 , 31 , 32 ] or to introduce sensitizers, providing absorption in the visible region. Therefore, semiconductors of A 2 B 6 group (CdS, E g = 2.4 eV; CdSe, E g = 1.7 eV) and A 3 B 5 group (InP, E g = 1.35 eV) [ 28 , 33 , 34 , 35 , 36 ], as well as organic dyes (i.e., macrocyclic and heterocyclic complexes of transition metals [ 38 , 39 , 40 ]), are investigated.…”