Nanostructured dielectric and metallic photonic architectures can concentrate the electric field through resonances, increase the light optical path by strong diffraction and exhibit many other interesting optical phenomena that cannot be achieved with traditional lenses and mirrors. The use of these structures within actual devices will be most beneficial for enhanced light absorption in thin solar cells, photodetectors and to develop new sensors and light emitters. However, emerging optoelectronic devices rely on large area and low cost fabrication routes such as roll to roll or solution processing, to cut manufacturing costs and increase the production throughput. If the exciting properties exhibited photonic structures are to be implemented in these devices then, they too have to be processed in a similar fashion as the devices they intend to improve. In this presentation, I will describe different low cost and large area photonic architectures that coupled to solution processed solar cells, photodetectors and SERS sensors facilitate enhanced light matter interaction within the active layer and are fully compatible with current manufacturing processes.
The solar-to-electric power conversion efficiency of dye sensitized solar cells can be greatly enhanced by integrating a porous and highly reflecting photonic crystal in the device. The light harvesting enhancement is based on the enlargement of optical absorption caused by longer matter-radiation interaction time, which takes place at certain ranges of wavelengths. Photons are localized within the dye-sensitized electrode due to the effect of the photonic crystal, so the probability of optical absorption, and therefore the photogenerated current, is enhanced. The proposed photonic crystals are porous to allow a proper flow of the electrolyte through it and to prevent the introduction of internal resistance in the cell, which might alter the charge transport dynamics.
The light harvesting enhancement observed when photonic colloidal crystals are integrated in dye sensitized titanium
oxide solar cells is investigated herein. Such absorptance increment is explained in terms of slow photon propagation at
certain ranges of wavelengths lying within the photonic pseudogap and partial localization in an absorbing layer placed
onto the colloidal lattice. Based on those findings, not only recently reported experiments have been satisfactorily
explained, but also new optical designs for the dye-sensitized solar cells (DSSC) are proposed. The new arrangement
consists of piling up different lattice constant crystals leading to light harvesting enhancement in the whole dye
absorption range. We provide the optimum structural features of such photonic crystal multilayer needed to achieve a
photocurrent efficiency enhancement of around 60% with respect to standard dye-sensitized solar cells.
The light harvesting enhancement observed when photonic colloidal crystals are integrated in dye sensitized titanium oxide solar cells is investigated herein. Such absorptance increment is explained in terms of slow photon propagation at certain ranges of wavelengths lying within the photonic pseudogap and partial localization in an absorbing layer placed onto the colloidal lattice. Based on those findings, not only recently reported experiments have been satisfactorily explained, but also new optical designs for the dye-sensitized solar cells (DSSC) are proposed. The new arrangement consists of piling up different lattice constant crystals leading to light harvesting enhancement in the whole dye absorption range. We provide the optimum structural features of such photonic crystal multilayer needed to achieve a photocurrent efficiency enhancement of around 60% with respect to standard dye-sensitized solar cells.
Herein we present different results on the application of spin-coating to the processing of thin films made of spherical colloids ordered in three dimensional structures. We focus on the infiltration and controlled introduction of optical planar defects. We show that the use of spin-coating largely diminishes the processing time scales typically used in the field of colloidal crystals, and still allows one to attain high quality structures. We demonstrate that spin-coating permits the controlled infiltration of colloidal crystals with many different types of compounds. Examples are given for different oxide and polymer guest compounds introduced in the voids of the colloidal lattices. Both scanning electron microscopy and optical spectroscopy evidence of such control are provided. We also show that a thin layer of particulate material can be spread onto a colloidal crystal by spin coating a suspension of such particles in which control over the aggregation state has been achieved first. This gives rise to a capped lattice that present surface resonant modes and can be used to build a planar defect embedded in the bulk. In all cases, evidence of the optical quality of the different samples made is provided.
We present a bottom-up approach for the construction of tunable functional defects in colloidal photonic crystals (CPCs). These structures incorporate polyelectrolyte multilayer (PEM) planar defects embedded in silica CPCs through a combination of evaporation induced self-assembly and microcontact transfer printing. We show how the enormous chemical diversity inherent to PEMs can be harnessed to create chemically active defect structures responsive to solvent vapor pressures, light, temperature as well as redox cycling. A sharp transmission state within the photonic stopband, induced by the PEM defect, can be precisely, reproducibly and in some cases reversibly tuned by these external stimuli. These materials could find numerous applications as optically monitored chemical sensors, adjustable notch filters and CPC-based tunable laser sources.
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