Search results for "Energy conversion"

Quasi-phase-matched third harmonic generation in optical fibers using refractive-index gratings

2011

International audience; The purpose of this work is to demonstrate the quasi-phase-matching of third harmonic generation process in optical fibers using refractive-index gratings. We compare conversion efficiency calculated with analytical coupled modes theory and numerical approach employing system of coupled generalized nonlinear Schrödinger equation. Moreover, we show that introducing the phase matching condition that takes into account the nonlinear contribution to propagation constants significantly increases the conversion efficiency by several orders of magnitude. Finally we optimize the grating constant to maximize conversion efficiency.

Boosting Long-Term Stability of Pure Formamidinium Perovskite Solar Cells by Ambient Air Additive Assisted Fabrication

2021

Due to the high industrial interest for perovskite-based photovoltaic devices, there is an urgent need to fabricate them under ambient atmosphere, not limited to low relative humidity (RH) conditions. The formamidinium lead iodide (FAPI) perovskite α-black phase is not stable at room temperature and is challenging to stabilize in an ambient environment. In this work, we show that pure FAPI perovskite solar cells (PSCs) have a dramatic increase of device long-term stability when prepared under ambient air compared to FAPI PSCs made under nitrogen, both fabricated with N-methylpyrrolidone (NMP). The T80 parameter, the time in which the efficiency drops to 80% of the initial value, increases f…

Energy conversion efficiency in betavoltaic cells based on the diamond Schottky diode with a thin drift layer

2020

The HPHT diamond Schottky diode was assembled as a Metal/Intrinsic/p-doped structure betavoltaic cell (BC) with a very thin (1 μm) drift layer and tested under 5–30 keV electron beam irradiation using a scanning electron microscope (SEM). The effect of the β-radiation energy and the backscattering of electrons on the energy conversion was studied. From the results obtained, it is shown that, the efficiency of the investigated BC increases from 1.01 to 3.75% with the decrease of β-particle energy from 30 to 5 keV due to an increase of the electron beam absorption in a thin drift layer. Maximum efficiency is achieved when the electron beam energy is close to the average β-decay energy of 3H. …

Performance of dye-sensitized solar cells based on novel sensitizers bearing asymmetric double D−π−A chains with arylamines as donors

2012

Abstract Three novel, metal-free organic sensitizers bearing two asymmetric double donor-π-acceptor (D-π-A) chains ( DC1 - 3 ), each, and a reference dye containing single D-π-A chain ( SC ) with cyanoacrylic acid as electron acceptor are synthesized. Their photophysical, electrochemical properties and the performances of the corresponding dye-sensitized solar cells (DSSCs) are further investigated. The dyes, DC1, DC2 and DC3 contain one chain with diphenylamine and another chain with carbazole or phenothiazine as electron donor, while diphenylamine is only employed as electron donor in SC . Compared to the inferior solar energy to electricity conversion efficiency ( η ) of 2.82%, 4.66% and…

Synthesis of Circumpyrene by Alkyne Benzannulation of Brominated Dibenzo[hi,st]ovalene

2019

A transition-metal catalyzed alkyne benzannulation allowed an unprecedented synthesis of circumpyrene, starting from 3,11-dibromo-6,14-dimesityldibenzo[hi,st]ovalene (DBOV). The circumpyrene was characterized by a combination of NMR, mass spectrometry, and single-crystal X-ray diffraction analysis, revealing its multizigzag-edged structure. Two newly introduced C═C bonds in circumpyrene strongly perturbed the electronic structures of DBOV, as evidenced by increased optical and electrochemical energy gaps. This is in good agreement with an increased number of Clar's sextets as well as a decreased number of π-electrons in the conjugation pathway of circumpyrene, according to anisotropy of the…

Perovskite solar cells prepared by flash evaporation

2015

A simple vacuum deposition method for the preparation of high quality hybrid organic-inorganic methylammonium lead iodide perovskite thin films is reported. When sandwiched in between organic charge transporting layers, such films lead to solar cells with a power conversion efficiency of 12.2%.

Correlation between polymer architecture, mesoscale structure and photovoltaic performance in side-chain-modified poly(p-arylene-ethynylene)-alt-poly…

2011

Abstract Recent investigations have shown that an anthracene containing poly( p -arylene-ethynylene)-alt-poly( p -arylene-vinylene) statistical copolymer consisting of a well defined conjugated backbone, along which linear and branched alkoxy side chains are attached in a random manner, yields, compared to its counterparts with regular side chain substitution, an improved performance in polymer [6,6]:-phenyl-C 61 -butyric acid methyl ester (PCBM) bulk-heterojunction solar cells. The microscopic origin for the improved power conversion efficiency ( η  ≈ 3.8%) of the statistical copolymer – which is the best in its material class – has not been resolved. We conducted grazing incidence wide-an…

Metal-Oxide-Free Methylammonium Lead Iodide Perovskite-Based Solar Cells: the Influence of Organic Charge Transport Layers

2014

Metal-oxide-free methylammonium lead iodide perovskite-based solar cells are prepared using a dual-source thermal evaporation method. This method leads to high quality reproducible films with large crystal domain sizes allowing for an in depth study of the effect of perovskite film thickness and the nature of the electron and hole blocking layers on the device performance. The power conversion efficiency increases from 4.7% for a device with only an organic electron blocking layer to almost 15% when an organic hole blocking layer is also employed. In addition to the in depth study on small area cells, larger area cells (approx. 1 cm(-2)) are prepared and exhibit efficiencies in excess of 10…

Photovoltaic Properties of a Porphyrin-Containing Polymer as Donor in Bulk Heterojunction Solar Cells With Low Energy Loss

2017

High‐Efficiency Perovskite Solar Cells Using Molecularly Engineered, Thiophene‐Rich, Hole‐Transporting Materials: Influence of Alkyl Chain Length on …

2016

The synthesis and characterization of a series of novel small-molecule hole-transporting materials (HTMs) based on an anthra[1,2-b:4,3-b′:5,6-b′′:8,7-b′′′]tetrathiophene (ATT) core are reported. The new compounds follow an easy synthetic route and have no need of expensive purification steps. The novel HTMs are tested in perovskite solar cells and power conversion efficiencies (PCE) of up to 18.1% under 1 sun irradiation are measured. This value is comparable with the 17.8% efficiency obtained using 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene as a reference compound. Similarly, a significant quenching of the photoluminescence in the first nanosecond is observed, ind…