Search results for "Solar Cell"
showing 10 items of 410 documents
Low-cost high-haze films based on ZnO nanorods for light scattering in thin c-Si solar cells
2015
Light scattering from ZnO nanorods (NR) is investigated, modeled, and applied to a solar cell. ZnO NR (120-1300 nm long, 280-60 nm large), grown by low-cost chemical bath deposition at 90 degrees C, exhibit diffused-to-total transmitted light as high as 70% and 30% in the 400 and 1000 nm wavelength range, respectively. Data and scattering simulation show that ZnO NR length plays a crucial role in light diffusion effect. A transparent ZnO NR film grown on glass and placed on top of a 1 mu m thick c-Si solar cell is shown to enhance the light-current conversion efficiency for wavelengths longer than 600 nm. (C) 2015 AIP Publishing LLC.
Density of States characterization of TiO2 films deposited by Pulsed Laser Deposition for Heterojunction solar cells
2021
The application of titanium dioxide (TiO2) in the photovoltaic field is gaining traction as this material can be deployed in doping-free heterojunction solar cells with the role of electron selective contact. For modeling-based optimization of such contact, knowledge of the titanium oxide defect density of states is crucial. In this paper, we report a method to extract the defect density through nondestructive optical measures, including the contribution given by small polaron optical transitions. The presence of both related to oxygen-vacancy defects and polarons is supported by the results of optical characterizations and the evaluation of previous observations resulting in a defect band …
Influence of doped charge transport layers on efficient perovskite solar cells
2018
Planar vacuum deposited p–i–n methyl ammonium lead tri-iodide perovskite solar cells are prepared with different electron and hole transporting layers, either doped or undoped. The effect of these layers on the solar cells performance (efficiency and stability) is studied. The main benefit of using doped layers lies in the formation of barrier free charge extraction contacts to the electrodes. However, this comes at the cost of increased residual absorption (reducing the current density and efficiency of the cells) and a decreased stability. A generic solar cell structure using undoped charge extraction layers is presented, containing a thin layer of a strong electron acceptor in between th…
Modulating the luminance of organic light-emitting diodes via optical stimulation of a photochromic molecular monolayer at transparent oxide electrode
2020
Nanoscale 12(9), 5444-5451 (2020). doi:10.1039/D0NR00724B
Luminescence properties of III-V multi-junctions solar cells
2012
The recent achievement of multi-junctions solar cells, based on III-V semiconductors, exceeding 43% efficiency, has stimulated a rapid growth of concentration photovoltaic (CPV) technology. The large efficiency of these cells is based on the matching between the semiconductors band gap and the solar spectrum and the capability of working under concentrated illumination, up to ~1000 suns. The research pays, therefore, attention to investigate in detail the mechanisms that affect the conversion efficiency, such as the non radiative losses that increase the cell temperature thus favoring the electron-hole (e-h) recombination. With the aim to clarify the performances of these III-V cells, here …
The origin of slow electron recombination processes in dye-sensitized solar cells with alumina barrier coatings
2004
We investigate the effect of a thin alumina coating of nanocrystalline TiO2 films on recombination dynamics of dye-sensitized solar cells. Both coated and uncoated cells were measured by a combination of techniques: transient absorption spectroscopy, electrochemical impedance spectroscopy, and open-circuit voltage decay. It is found that the alumina barrier reduces the recombination of photoinjected electrons to both dye cations and the oxidized redox couple. It is proposed that this observed retardation can be attributed primarily to two effects: almost complete passivation of surface trap states in TiO2 that are able to inject electrons to acceptor species, and slowing down by a factor of…
Improving Perovskite Solar Cells: Insights From a Validated Device Model
2017
To improve the efficiency of existing perovskite solar cells (PSCs), a detailed understanding of the underlying device physics during their operation is essential. Here, a device model has been developed and validated that describes the operation of PSCs and quantitatively explains the role of contacts, the electron and hole transport layers, charge generation, drift and diffusion of charge carriers and recombination. The simulation to the experimental data of vacuum-deposited CH3NH3PbI3 solar cells over multiple thicknesses has been fit and the device behavior under different operating conditions has been studied to delineate the influence of the external bias, charge-carrier mobilities, e…
State selective electron injection in non-aggregated titanium phthalocyanine sensitised nanocrystalline TiO2 films
2004
We describe a novel titanium phthalocyanine that shows no aggregation when anchored to nanocrystalline TiO2 films through its axial carboxylated ligand without the use of co-adsorbents; state selective electron injection into the TiO2 is demonstrated, resulting in efficient photocurrent generation in dye sensitised photoelectrochemical solar cells. Palomares Gil, Emilio J, epagil@alumni.uv.es
Vacuum processed perovskite solar cells
2017
El objetivo de la tesis es el desarrollo de materiales y métodos de deposición de capas de perovskita utilizando procesos de alto vacío, principalmente mediante co-evaporación. Para la fabricación de los dispositivos, se han empleado y optimizado diferentes materiales transportadores de electrones y de huecos. La tesis está estructurada de la siguiente manera:Capítulo 1: se desarrolla un método de deposición novedoso para la preparación de capas delgadas de perovskitas mixtas iodo-bromo.Capítulo 2: se presenta el estudio de diferentes derivados del fullereno como materiales transportadores de electrones para conseguir células solares de perovskita de alta eficiencia.Capítulo 3: se optimiza …
Single junction and tandem perovskite solar cells
2017
En este trabajo hemos estudiado diferentes métodos para preparar dispositivos fotovoltaicos de perovskitas. Se han cumplido los tres objetivos definidos al inicio de este periodo de investigación: 1. Hemos establecido con éxito un método estable y reproducible para la fabricación de células solares de perovskita procesadas desde disolución, empleando acetato de plomo y MAI como materiales precursores. 2. Hemos conseguido sintonizar el "bandgap" de perovskitas mixtas de bromuro y yoduro para alcanzar un valor de 2.0 eV, aprovechando las propiedades estabilizadoras de los cationes Cs+ y FA. Hemos investigado perovskitas de doble halogenuro y doble catión Cs0.15FA0.85Pb(Br0.7I0.3)3, fabricadas…