Browsing by Subject "Energy conversion"

Now showing 1 - 5 of 5

Open Access
Atomic layer deposition: an enabling technology for the growth of functional nanoscale semiconductors
(Institute of Physics Publishing, 2017) Bıyıklı, Necmi; Haider A.
In this paper, we present the progress in the growth of nanoscale semiconductors grown via atomic layer deposition (ALD). After the adoption by semiconductor chip industry, ALD became a widespread tool to grow functional films and conformal ultra-thin coatings for various applications. Based on self-limiting and ligand-exchange-based surface reactions, ALD enabled the low-temperature growth of nanoscale dielectric, metal, and semiconductor materials. Being able to deposit wafer-scale uniform semiconductor films at relatively low-temperatures, with sub-monolayer thickness control and ultimate conformality, makes ALD attractive for semiconductor device applications. Towards this end, precursors and low-temperature growth recipes are developed to deposit crystalline thin films for compound and elemental semiconductors. Conventional thermal ALD as well as plasma-assisted and radical-enhanced techniques have been exploited to achieve device-compatible film quality. Metal-oxides, III-nitrides, sulfides, and selenides are among the most popular semiconductor material families studied via ALD technology. Besides thin films, ALD can grow nanostructured semiconductors as well using either template-assisted growth methods or bottom-up controlled nucleation mechanisms. Among the demonstrated semiconductor nanostructures are nanoparticles, nano/quantum-dots, nanowires, nanotubes, nanofibers, nanopillars, hollow and core-shell versions of the afore-mentioned nanostructures, and 2D materials including transition metal dichalcogenides and graphene. ALD-grown nanoscale semiconductor materials find applications in a vast amount of applications including functional coatings, catalysis and photocatalysis, renewable energy conversion and storage, chemical sensing, opto-electronics, and flexible electronics. In this review, we give an overview of the current state-of-the-art in ALD-based nanoscale semiconductor research including the already demonstrated and future applications.
Open Access
Ion sensing, light harvesting, energy conversion & self-assembly in rationally designed molecular constructs
(2013) Büyükçakır, Onur
In this thesis, we have constructed rationally designed functional supramolecular systems. In the first chapter, we reported two Bodipy based chemodosimeters to detect fluoride both in solution and in polymethylmethaacraylate (PMMA) matrix. In the second part, we synthesized tetrastyrl-Bodipy derivatives by condensing methyl substituents of 1,3,5,7-tetramethyl-Bodipy dyes with different aromatic aldehydes. The resulting dyes have sharp and intense emission maxima in the near-IR region and they are robust candidates for functional supramolecular systems because of their outstanding properties. In next chapter, we investigated light harvesting properties of these new generation near-IR emissive dyes. In designed light harvesters, a near-IR emissive tetrastyrl-Bodipy dye which was decorated with short wavelength Bodipy fluorophores function as antenna units. In the forth chapter, we reported a Cu(I)-diimine complex as a photosensitizer for dye-sensitized solar cells (DSSC). It was demonstrated that Cu(I) diimine complex with capability of ultrafast electron injection to TiO2 nanoparticles can be a very good candidate for replacing ruthenium based polypyridyl complexes with a much lower cost. This research potentially can generate significant impact for those working on solar energy conversion and DSSC. In the final chapter, we propose to utilize oscillations in pH to move the two components of pseudorotoxane in relation to each other and this is the first example of a pseudorotaxane in which the mobile component is shuttling autonomously.
Open Access
Nanosecond sum-frequency generating optical parametric oscillator using simultaneous phase matching
(Optical Society of American (OSA), 2005) Figen, Z.G.; Aytür O.
We report a nanosecond sum-frequency generating optical parametric oscillator based on a single KTiOAsO4 crystal that is simultaneously phase matched for optical parametric generation and sum-frequency generation. Pumped at a wavelength of 1064 nm by a Q-switched Nd:YAG laser, this device produces 10.4-ns-long 8.3 mJ red pulses at a wavelength of 627 nm with 21% energy conversion efficiency. This device provides a simple and efficient method for converting high energy Nd:YAG lasers to a red wavelength. © 2005 Optical Society of America.
Open Access
Photonic metamaterial absorber designs for infrared solar-cell applications
(SPIE, 2010) Alıcı, Kamil Boratay; Özbay, Ekmel
We propose a metamaterial based absorber design that operates at the infrared regime. The absorption peak was 83.6%. We can incorporate solar-cell layers inside the metamaterial absorber in order to significantly increase solar-cell efficiency. © 2010 SPIE.
Open Access
Semiconductor-less photovoltaic device
(IEEE, 2013) Atar, Fatih B.; Battal, Enes; Aygun, Levent E.; Dağlar, Bihter; Bayındır, Mehmet; Okyay, Ali Kemal
We demonstrate a novel semiconductor-less photovoltaic device and investigate the plasmonic effects on this device structure. The device is made of metal and dielectric layers and the operation is based on hot carrier collection. We present the use of surface plasmons to improve energy conversion efficiency. The field localization provided by surface plasmons confine the incident light in the metal layer, increasing the optical absorption and hot electron generation rate inside the metal layer. The device consists of two tandem MIM (metal-insulator-metal) junctions. Bottom MIM junction acts as a rectifying diode and top MIM junction is used to excite surface plasmons. The device operation principle as well as the topology will be discussed in detail. © 2013 IEEE.