EFFECT OF PLASMONIC NANOSTRUCTURES ON THE OPTICAL PROPERTIES OF CH3NH3PBI PEROVSKITE FILMS

This paper investigated the optical properties of both silver island films (SIF) and CH3NH3PbI3 perovskite films obtained on the surface of SIF. It was found that the surface morphology of SIF has a substantial effect on the optical density of perovskite films. Furthermore, a significant redshift in the absorption spectrum of the island films was observed when perovskite is deposited on them. The intensity and lifetime of the luminescence of perovskite films on the surface of the island films depend on the wavelength of the exciting light...

Sensitiztion of TiO2 by merocyanine dye in the prescence of plasmon nanoparticles

Currently, an active search and study of non-metal organic luminophores for dye-sensitized solar cells is peformed. Merocyanine dyes are characterized by high bipolarity, narrow selective absorption bands, high absorption cross sections (extinctions) and high photochemical stability. In present work we have studied the effect of Ag nanoparticles (NPs) on the sensitization of a TiO2 film by merocyanine dye. For this purposes dye was adsorbed onto porous TiO2 films with the addition of Ag/TiO2 core-shell nanostructures at a concentration of 0, 0.5, 1, and 2 wt%. These nanostructures consist of a core – Ag nanoparticles (20 nm in diameter) and a TiO2 shell with a thickness of 4 nm. These TiO2 films were used both for spectral-luminescence measurements and for DSSC assembling according to a standard technique. The absorption spectrum of merocyanine is located in the region of 500 – 650 nm with a maximum at 590 nm, the fluorescence band is centered at 630 nm. The measurements showed that the addition of Ag/TiO2 NPs does not affect on the shape and position of the absorption and fluorescence bands of the dye. In the presence of plasmonic NPs, a 30% increase in the fluorescence intensity of the dye was recorded. The fluorescence lifetime of the dye practically does not change in the presence of Ag/TiO2 NPs. The current–voltage characteristics (CVC) of solar cells were measured under the illumination with a Xe lamp with a power of 100 mW/cm2 . The merocyanine dye has the following photovoltaic parameters: Isc=0.18 mA/cm2, Voc=355 mV, FF=0.33, η=0.21%. The addition of Ag/TiO2 NPs doubles the efficiency of the DSSC sensitized with a merocyanine dye and Isc=0.6 mA/cm2 , Voc=373 mV, FF=0.20, η=0.43%. The data on the spectral sensitivity of DSSC show that the addition of Ag/TiO2 NPs results in the growth in the spectral sensitivity of the solar cell in the absorption band of the dye. At the same time, absorption of plasmonic Ag NPs was recorded in the region of 420 nm. Thus, the combinatioin of the growth of fluorescence and spectral sensitivity of solar cells with Ag/TiO2 NPs leads to an increase in the efficiency of the generation of charge carriers in a semiconductor sensitized by the investigated merocyanine

Laser modification of structure and optical properties of N-doped graphene oxide

The effect of laser ablation of N-doped graphene oxide (NGO) sheets on its optical properties has been studied. It was shown that the average lateral size of NGO sheets was decreased from 644.4 ± 143.8 to 114.4 ± 59.8 nm after 60 min of ablation. The data of FTIR spectroscopy have shown that after ablation the intensity of the vibrations bands of N-containing groups increases. The optical density of NGO dispersions and the intensity of their emission are depended on the ablation time. The highest fluorescence intensity was recorded upon excitation at a wavelength of 350 nm. For all NGO samples after laser irradiation a noticeable increase in the fluorescence intensity was registered. The enhancement factor was equal to ∼11.0 and 8.5 times for 30 and 60 min, respectively. The lifetime of NGO fluorescence after ablation was increased from 1.73 ns to 3.63 ns. After ablation, the samples under study exhibit long-term luminescence with a maximum at about 450 nm. The data obtained open up possibilities to control the optical properties of N-doped graphene oxide and nanodots based on it

Получение и исследование свойств диспергированного оксида графена

В данной работе изучена способность оксида графена формировать стабильные дисперсии в органических растворителях. Показано, что обработка растворов графена ультразвуком приводит к уменьшению размеров частиц. Была исследована стабильность приготовленных дисперсий графена при измерении распределения числа частиц от их размеров и по изменению оптической плотности растворов во времени. Выяснено, что в тетрагидрофуране и диметилформамиде оксид графена формирует более стабильные дисперсии, чем в хлороформе и ацетоне

Bioinspired study of energy and electron transfer in photovoltaic system

This study focuses on understanding the fundamentals of energy transfer and electron transport in photovoltaic devices with uniquely designed nanostructures by analysing energy transfer in purple photosynthetic bacteria using dye-sensitised solar cell systems. Förster resonance energy transfer between the xanthene dye (donor of energy) and a new polymethine dye (acceptor of energy) was studied in dye-sensitised solar cells, which leads to a doubling of energy conversion efficiency in comparison to the cell with only the polymethine dye. The electron transport in the two different nanostructures of zinc oxide (nanorods and nanosheets) was investigated by spectroscopic methods (UV-vis spectrometer, time-resolved photoluminescence spectroscopy) and electrochemical potentiostat methods. The nanosheet structure of zinc oxide showed high short circuit current and long diffusion length. This fundamental study will lead to efficient artificial photosystem designs

Recent progress on perovskite materials in photovoltaic and water splitting applications

Abstract Both inorganic and hybrid (organo-inorganic) perovskite materials are potential candidates as photocatalysts for use in both photovoltaic (PV) and photocatalytic water splitting applications. Currently, research has been focused on specifically designing perovskite materials so they can harness the broad spectrum of the visible light wavelength. Inorganic perovskites such as titanates, tantalates, niobates, and ferrites show great promise as visible light-driven photocatalysts for water splitting, whereas hybrid perovskites such as methylammonium lead halides reveal unique photovoltaic and charge transport properties. The main objective of this article is to examine the progress on some recent research on perovskite nanomaterials for both solar cell and water splitting applications. This mini review paper summarizes some recent developments of organic and inorganic perovskite materials (PMs) and provides useful insights for their future improvement

Bioinspired study of energy and electron transfer in photovoltaic system

<p>This study focuses on understanding the fundamentals of energy transfer and electron transport in photovoltaic devices with uniquely designed nanostructures by analysing energy transfer in purple photosynthetic bacteria using dye-sensitised solar cell systems. Förster resonance energy transfer between the xanthene dye (donor of energy) and a new polymethine dye (acceptor of energy) was studied in dye-sensitised solar cells, which leads to a doubling of energy conversion efficiency in comparison to the cell with only the polymethine dye. The electron transport in the two different nanostructures of zinc oxide (nanorods and nanosheets) was investigated by spectroscopic methods (UV-vis spectrometer, time-resolved photoluminescence spectroscopy) and electrochemical potentiostat methods. The nanosheet structure of zinc oxide showed high short circuit current and long diffusion length. This fundamental study will lead to efficient artificial photosystem designs.</p