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Room temperature (RT) synthesis of the ternary cesium lead bromide CsPbBr3 quantum dots with oleic acid and oleylamine ligands was developed by Zeng and coworkers in 2016. In their works, the supersaturated recrystallization (SR) was adopted as a processing method without requiring inert gas and high-temperature injection. However, the oleic acid ligand for haloplumbate is known to be relatively unstable. Hence, in this work, we employed the eco-friendly olive oil to replace the oleic acid portion for the SR process at RT. Resultantly, we found that the cube-shaped nanocrystal has a size of ~40–42 nm and an optical bandgap of ~2.3 eV independent of the surface ligands, but the photoluminescence lifetime (τav) and crystal packing are dependent on the ligand species, e.g., τav = 3.228 ns (olive oil and oleylamine; here less ordered) vs. 1.167 ns (oleic acid and oleylamine). Importantly, we explain the SR mechanism from the viewpoint of the classical LaMer model combined with the solvent engineering technique in details.

The exploration and harnessing of the renewable sources of energy, in addition to that of the conventional sources, has become significantly prominent with the increasing global energy demands for the continuous production of the energy for world consumption. Among these sources, for different applications, the approach of harnessing of the solar energy using the solar cells based on organic materials has already been envisaged as an alternative to that of using the solar cells based on silicon, with much of focus on the polymer based solar cells, and more recently perovskite solar cells. Such applications require the unique property of flexibility of the solar cells based on solution processable active materials. In addition, as the required area of the solar cells for these applications can be very large, the upscaling of the manufacturing rate and the size of these solar cells requires the manufacturing of these solar cells with faster techniques of roll-to-roll printing, which allow the faster and massive commercial scale for production. This review gives a detailed account of the recent progress and the development of the roll-to-roll printing technology for the polymer and perovskite solar cells, including the roll-to-roll-compatible materials and processes, over few years.

In this report, we report the intensity dependant nonlinear absorption properties of bio-inspired hybrid materials (betanin-ZnO) embedded in polymeric matrices through the Z-scan technique using an Nd: YAG laser (532 nm, 7 ns, 10 Hz). We observed a change over in the sign of nonlinearity due to the interplay of exciton bleaching and optical limiting mechanisms. Light confinement effect and ship-in-a bottle effect play crucial roles. Theoretical analysis has been performed using a model based on nonlinear absorption coefficient and saturation intensity. The result of present study gives an additional mechanism for the gain enhancement in dye doped ZnO matrix.

Performance of dye sensitized solar cells based on betanin natural dye from red beets with various nanostructured photoanodes on transparent conducting glass has been investigated. In four different electrolyte systems cell efficiency of 2.99% and overall photon to current conversion efficiency of 20% were achieved using ZnO nanosheet electrode with iodide based electrolyte in acetonitrile solution. To enhance solar harvesting in organic solar cells, uniform sized metal nanoparticles (gold (Au) of ~ 8 nm) synthesized via microwave irradiation method were incorporated into the device consisting of ZnO. Enhanced power conversion efficiency of 1.71% was achieved with ZnO/Au nanocomposite compared to the 0.868% efficiency of the bare ZnO nanosheet cell with ferrocene based electrolyte.

We present the linear and nonlinear optical studies of a natural dye betacyanin extracted from red beet root in the presence of silver nano particles in colloidal solution. We synthesized silver nano particles and characterized by XRD and HRTEM. We show how appropriate concentration of silver nanoparticles can enable tuning of dye fluorescence efficiency. Nonlinear properties are studied using open aperture Z scan technique with Nd:YAG laser (532 nm, 7 ns, 10 Hz). We show modification of nonlinear properties for the dye to the desired level can be achieved in the presence of silver nanoparticles. High nonlinearity we also demonstrated in PVA/Ag nano/Betacyanin composite films. Theoretical analysis is performed using model based on nonlinear absorption of materials and scattering of metal nanoparticles.

We report a methodical study about the third order optical nonlinearity of anisotropic growth of ZnO crystals embedded in polymeric matrices and nanowires on the glass substrate with the use of preexisting textured ZnO, ZnS and TiO2 seeds using a Z-scan method with Nd:YAG laser (532 nm, 7 ns, 10 Hz). The studies show that the optical nonlinearity of ZnO crystals is highly dependent on the structural geometry and the correlation of semiconductor. Our study offers better insights into the thirdorder nonlinear optical characteristics of ZnO crystals and reveals great potential for applications in nonlinear photonic devices.

ZnO micro-crystals had been successfully fabricated on a large scale under mild conditions without any additives, templates or substrates, exhibiting a hexagonal wurtzite structure and grown along the [001] direction. Effects of the reactant concentration and temperature on the sizes and morphologies of the ZnO products had been investigated. The optical absorptive nonlinearity of the ZnO/PVA composites was analyzed using an open aperture and a closed Z-scan technique shows a negative value for nonlinear refractive index n2. Stability as well as the mechanical properties of the crystals embedded in the PVA matrix makes them more suitable for device fabrication as compared to the ZnO crystals dispersed in solution.

We report on the optical characterization, including linear and non linear, of ZnO nanoplates embedded in PVA. Nonlinear optical characterization of these films was studied by the Z-scan technique using an Nd:YAG laser (532 nm, 7 ns, 10 Hz).The studies show that the material is highly nonlinear, have desirable lower optical liming threshold of 46.86 MW/cm2 at pump power of 436 MW/cm2 and with negative refractive index. Therefore, these films with immobilized semiconductor nanoplates appear to be attractive candidates for optical limiting applications.

We report on the solvent effect on the third order optical nonlinearity of betanin natural dye extracted from red beet root and their third order nonlinear optical (NLO) properties have been studied using a Q-switched Nd:YAG laser at 532 nm. The third order nonlinearity of these samples are dominated by nonlinear absorption, which leads to strong optical limiting and their strength is influenced by the solvent used, suggesting that betanin natural dyes are promising candidate for the development of photonic nonlinear optic devices.

The growth of Zinc Oxide (ZnO) microrods by wet chemical method, under prolonged treatment of zinc nitrate for 22 h in low temperature (80 °C) with hexamine is presented. The purpose was to obtain large microrods that can act as laser resonators with emission in the blue region. The electron microscopy and X-ray diffraction observations reveal that the ZnO microrods are single crystalline. We have done various optical characterizations in order to assess the suitability of the rods in photonic applications. Studies include optical absorption, fluorescence and photon backscattering. Room temperature optical measurements reveal that they have a large direct band gap of 3.7 eV and an emission at the visible and ultraviolet region and have excitation wavelength dependence. The backscattering studies clearly reveal the photon confinement effects, which is the first test of the material's self lasing action.

Light absorption and scattering of metal nano partilces occur in very narrow range of wavelengths. This is also dependent on the geometry and shape of metal nano particles. It is also known that scattering is related to (volume)2 and absorption is related to the volume of the spherical metal nano particles. In our work we show that using this principle metal nano particles enable fluorescence tuning of dyes. In our experiment we show such tuning in naturally occurring betacyanin extracted from red beetroot. We also show that such tuning is dependent on the size variation of the silver nano particles.

We demonstrate coherent back scattering and random lasing from an active random media of Rhodamine 6G doped polymer optical fiber particles on different sizes. Narrow emission modes are observed experimentally over a broad range of scattering strengths without requiring optical cavities. The particle-size dependence of transport mean free path, which measured from coherent backscattering measurements. Since the scattering mean free path is less than the emission wavelength, recurrent light scattering arises and provides coherent feedback for lasing. Laser emission from the sample observed in all directions. This observation also provides direct evidence for the existence of recurrent scattering of light. The lasing threshold intensity depends on the excitation volume, also the decrease of the lasing threshold at large particle size. The feedback for lasing originates mainly from backscattering of particles near the boundaries of the pumped region. Here, the lasing threshold depends strongly on the size distribution, dye concentration and intensity of excitation in the ensemble.

We have studied the structural and optical properties of ZnO micro rods. These rods are synthesized by low temperature hydrothermal method, which is under the treatment of 80 °c/22 hrs. The synthesized rods have an average length of 5 μm with hexagonal cross section. They are characterized by absorption spectrum, fluorescence spectrum, back scattering, SEM, HRTEM, and SAED. The photoluminescence from the spectrophotometer shows broad visible emission.

The performance of dye sensitized solar cells (DSSCs) depends on the collective contribution from its constituents which include the nanoparticle film, dye, electrolyte, and the counter electrode. In this report, we have tried to elucidate the varying performance of the TiO2 based DSSCs standardised using N719 dye and Platinum as counter electrode with various electrolytes including quasi static electrolytes. We have also evaluated the photovoltaic characteristics of the cells employing different morphological structured TiO2 photoanode. The DSSC based on the hierarchical anatase TiO2 nanotree photoelectrode showed the highest light-to-electricity conversion efficiency of 10.2%.

This paper describes the optical limiting performance of 2D ZnO nanoflakes and plates synthesized through a simple wet chemical method. Scanning electron microscopic imaging of these nanostructures revealed the shape evolution from the nanoflakes to nanoplates as the growth duration increased from 11 h to 18 h. The nonlinear absorption is studied using open aperture Z scan technique. The process behind the nonlinear absorption is predicted as two photon absorption and one photon assisted energy transfer to the nearby trapping sites. We observe the appreciable optical limiting threshold of 46.86 MW/cm2 for high pump power of 436 MW/cm2 for nanoplates compared with nanoflakes (169.49 MW/cm2).

Erratum to ‘‘Synthesis of monocrystalline zinc oxide microrods by wet chemical method for light confinement applications’’ [Physica E 44 (2012) 2118–2123] Aparna Thankappan , Misha Hari , S. Mathew , Santhi Ani Joseph , Rolf Erni , Debajeet Bora , Artur Braun , V.P.N. Nampoori a International School of Photonics, Cochin University of Science and Technology (CUSAT), Cochin, India b Inter University Centre for Nanomaterials and Devices (IUCND), CUSAT, India c Center of Excellence in Lasers and Optoelectronic Sciences (CELOS), CUSAT, India d Laboratory for High Performance Ceramics, EMPA, Dubendorf, Switzerland e Electron Microscopy Center, EMPA, Dubendorf, Switzerland

We successfully synthesize four kinds of ZnO nano/microcrystals including dumbbell microrods, nanoflakes, nanoplates, and microrods by a simple wet chemical method. Growth duration is found to play a crucial role in the morphologies of these ZnO nano/microcrystallites. In addition, growth conditions are system-atically studied as a function of precursor concentration and temperature. The structural and optical characteristics of the ZnO samples are further investigated by X-ray diffraction, scanning electron microscopy, and photoluminescence spectroscopy.

In this article, we have investigated the effect of betanin natural dye extracted from red beetroot on nonlinear optical properties of ZnO nanoplates embedded in polymeric matrices through the Z-scan technique using an Nd: YAG laser (532 nm, 7 ns, 10 Hz). We observed reverse saturable absorption (RSA) at 532 nm for dye and ZnO nanoplates. A strong influence on RSA behavior of nanoplates-PVA matrix was observed by adding betanin natural dye. The influence of betanin on the nonlinear character of ZnO-PVA system leads to saturable absorption and again to RSA on increasing input fluence. Such a change over in the sign of the nonlinearity is due to the interplay of the exciton bleaching and optical limiting mechanisms, and probably due the presence of sucrose. Theoretical analysis has been performed using a model based on nonlinear absorption coefficient and saturation intensity. The result of present study gives an additional mechanism for the gain enhancement in dye doped ZnO matrix.