New cyclopropano 70 fullerene derivatives for the photovoltaic application

New cyclopropano 70 fullerenes derivatives were synthesised for photovoltaic (PV) application. The organic PV cells realized with these molecules blended with RR-P3HT polymer provided improved characteristics: 1.5% conversion efficiency (eta%), 9.29 mA/cm2 current density, 0.51 V open circuit voltage and 0.34 fill factor. The IPCE spectrum for P3HT: cyclopropano 70 fullerene cells shows a new peak around 430 nm with 71% external quantum efficiency. This explains the increased current density

Increase of the open circuit voltage by incorporation of functionalized SWNTs in a P3HT:PCBM photoactive layer

Date du colloque&nbsp;: 06/2009</p

Carboxylated and esterified SWCNTs : characterization and contribution as components of biomaterials and solar cells

Date du colloque&nbsp;: 04/2010</p

Increase of open circuit voltage of polymer bulk heterojunction solar cell by functionalized single walled carbon nanotubes

We report on an improvement of the open circuit voltage over 0.8 V, together with decent fill factor and large short circuit current, through the incorporation of ester-functionalized single wall carbon nanotubes in a poly(3-hexylthiophene): 1-(3-methoxycarbonyl) propyl-1-phenyl[6,6]C61 bulk heterojunction solar cell. The technique may open new margins for an extra efficiency enhancement through increase of the open circuit voltage using state of the art highly crystalline low band gap bulk heterojunction polymer solar cells

Improving the current density J(SC) of organic solar cells P3HT:PCBM by structuring the photoactive layer with functionalized SWCNTs

Several works concerning the incorporation of carbon nanotubes (CNTs) in bulk polymer RR-P3HT (regio-regular poly(3-hexylthiophene-2,5-diyl)):PCBM (methanofullerene phenyl-C-61-butyric-acid-methyl-ester) heterojunction have been already reported by a number of research groups. The optical and electrical properties of organic cells have been extensively studied. We investigated the incorporation of functionalized single wall carbon nanotubes (SWCNTs) into the matrix of P3HT:PCBM photovoltaic (PV) cells. The photovoltaic characteristics of the cells depend on the concentration of SWCNT. The incorporation of low concentrations of SWCNT in the photoactive layer increases the current density J(SC) before annealing and it can reach above 9 mA/cm(2). We attribute the improved PV performances to partial crystallization of the RR-P3HT. As revealed by XRD studies and confirmed by the absorbance spectra, which exhibit the typical shoulder at 600 nm and absorbance in the near infrared region. Interestingly, we observe also that doping the P3HT:PCBM active layer by the functionalized SWCNTs increases the open circuit voltage V-oc. (C) 2010 Elsevier B.V. All rights reserved

What this collaboration between artists and health-care leaders teaches us about living through COVID-19

A new project that spotlights the strain from COVID-19 on our health systems and the people who work in them has invited health-care leaders and artists to create artworks that illuminate what it has been like leading, working and living through the pandemic

New fullerene derivatives for the photovoltaic application

Cyclopropano[70]fullerenes have been synthesized in the aim of being used as acceptors in blends based on regioregular poly (3,5-Hexylthiophene) RR-P3HT for photovoltaic (PV) plastic cells. These molecules used with RR-P3HT in bulk heterojunction (BHJ) configuration provided interesting characteristics: 1.5% solar conversion efficiency, 9.29 mA/cm² current density, 0.51 V open circuit voltage, and 0.34 fill factor. The IPCE spectrum for P3HT: cyclopropano[70]fullerene cells shows a peak around 430 nm with 71% external quantum efficiency. This result justifies the increased current density

Age-related changes in matching novel objects across viewpoints

Peer reviewedPreprin

Visual acuity measured with luminance-modulated and contrast-modulated noise letter stimuli in young adults and adults above 50 years old

The human visual system is sensitive in detecting objects that have different luminance level from their background, known as first-order or luminance-modulated (LM) stimuli. We are also able to detect objects that have the same mean luminance as their background, only differing in contrast (or other attributes). Such objects are known as second-order or contrast-modulated (CM), stimuli. CM stimuli are thought to be processed in higher visual areas compared to LM stimuli, and may be more susceptible to ageing. We compared visual acuities (VA) of five healthy older adults (54.0±1.83 years old) and five healthy younger adults (25.4±1.29 years old) with LM and CM letters under monocular and binocular viewing. For monocular viewing, age had no effect on VA [F(1, 8)= 2.50, p> 0.05]. However, there was a significant main effect of age on VA under binocular viewing [F(1, 8)= 5.67, p< 0.05]. Binocular VA with CM letters in younger adults was approximately two lines better than that in older adults. For LM, binocular summation ratios were similar for older (1.16±0.21) and younger (1.15±0.06) adults. For CM, younger adults had higher binocular summation ratio (1.39±0.08) compared to older adults (1.12±0.09). Binocular viewing improved VA with LM letters for both groups similarly. However, in older adults, binocular viewing did not improve VA with CM letters as much as in younger adults. This could reflect a decline of higher visual areas due to ageing process, most likely higher than V1, which may be missed if measured with luminance-based stimuli alone

Age-related delay in information accrual for faces: Evidence from a parametric, single-trial EEG approach

Background: In this study, we quantified age-related changes in the time-course of face processing by means of an innovative single-trial ERP approach. Unlike analyses used in previous studies, our approach does not rely on peak measurements and can provide a more sensitive measure of processing delays. Young and old adults (mean ages 22 and 70 years) performed a non-speeded discrimination task between two faces. The phase spectrum of these faces was manipulated parametrically to create pictures that ranged between pure noise (0% phase information) and the undistorted signal (100% phase information), with five intermediate steps. Results: Behavioural 75% correct thresholds were on average lower, and maximum accuracy was higher, in younger than older observers. ERPs from each subject were entered into a single-trial general linear regression model to identify variations in neural activity statistically associated with changes in image structure. The earliest age-related ERP differences occurred in the time window of the N170. Older observers had a significantly stronger N170 in response to noise, but this age difference decreased with increasing phase information. Overall, manipulating image phase information had a greater effect on ERPs from younger observers, which was quantified using a hierarchical modelling approach. Importantly, visual activity was modulated by the same stimulus parameters in younger and older subjects. The fit of the model, indexed by R2, was computed at multiple post-stimulus time points. The time-course of the R2 function showed a significantly slower processing in older observers starting around 120 ms after stimulus onset. This age-related delay increased over time to reach a maximum around 190 ms, at which latency younger observers had around 50 ms time lead over older observers. Conclusion: Using a component-free ERP analysis that provides a precise timing of the visual system sensitivity to image structure, the current study demonstrates that older observers accumulate face information more slowly than younger subjects. Additionally, the N170 appears to be less face-sensitive in older observers