Improving the photovoltaic response of a poly(3-octylthiophene)/n-Si heterojunction by incorporating double-walled carbon nanotubes

Poly(3-octylthiophene)/n-Si heterojunction solar cells were studied with and without incorporation of double-walled carbon nanotubes (DWCNs) in the polymer layer. The performance of the device improves significantly by the incorporation of DWCNs. We report a power conversion efficiency, open circuit voltage, short-circuit current density and fill factor of 0.49%, 0.53 V, 5.9 mA cm−2 and 0.15 respectively for an un-optimized cell containing DWCNs. Reference cells without DWCNs show a much lower performance. DWCN incorporation yields better hole transport, easy exciton splitting and suppression of charge recombination, thereby improving photovoltaic action. DWCN seems a promising material for improving hole transport in organic solar cells

Improving photovoltaic response of poly„3-hexylthiophene…/n-Si heterojunction by incorporating double walled carbon nanotubes

Poly(3-hexylthiophene)/n-Si heterojunction solar cells were studied with and without incorporation of double walled carbon nanotubes (DWCNs) in the polymer layer. Performance of the device improves by manyfold by incorporation of DWCN. The authors report power conversion efficiency, open circuit voltage, short-circuit current density, and fill factor of 0.026%, 0.446 V, 0.3398 mA/cm2, and 0.17, respectively, for an unoptimized cell containing DWCN. Reference cells without DWCNs show much lower performance. DWCN incorporation yields better hole transport, easy exciton splitting, and suppression of charge recombination, thereby improving photovoltaic action. DWCN seems promising materials for improving hole transport in organic solar cells

Field electron emission of double walled carbon nanotube film prepared by drop casting method

Thick films of double walled carbon nanotubes (DWCN) were deposited on indium-tin-oxide (ITO) coated glass substrates by drop casting method and were studied for their field electron emission property in a parallel plate configuration using bare ITO coated glass as counter electrode. They show excellent field electron emission property with low turn-on-field of about 0.8 V/lm and threshold field of about 1.8 V/lm. Field enhancement factor calculated from the non-saturated region of the FN plot is about 1715. Field electron emission current was observed to be stable up to 3000 min, indicating thereby that DWCNs are excellent electron emitters with appreciable stable performance

Volatile organic compounds are ghosts for organic solar cells

All our efforts to demonstrate a multifunctional device – photovoltaic gas sensor (i.e. solar cell which show photovoltaic action depending on the gas / volatile organic compounds (VOC) in the surrounding atmosphere) yielded negative results. Photovoltaic performance of the organic solar cells under study degraded – almost permanently by exposing them to volatile organic compounds (VOCs). Although, the proposed multifunctional device could not be demonstrated; Present investigations yielded very important result that organic solar cells have problems not only with oxygen and humidity (known facts) but also with many VOCs and hazardous gases – making lamination / encapsulation step mandatory for their practical utilizatio

Role of echocardiography for assessment of cardiovascular haemodynamics during pregnancy

Background: Pregnancy is associated with volume overload producing significant vascular and hemodynamic adaptations in cardiovascular physiology. Present study was designed to follow up gradual adaptations in cardiovascular hemodynamics during the course of pregnancy using Doppler echocardiography which is reproducible and noninvasive technique.Methods: In present prospective study of 50 women, were divided into 2 groups of 25 each: control group & study group (pregnant patient in I trimester, II trimester & III trimester). They were non-invasively analysed for cardiovascular function and systemic hemodynamics using echocardiography and compared with control group. The data was analysed using ANOVA for comparison within the group and student’s t- test for comparison between the groups. p value <0.05 was considered to be significant.Results: Mean age and height in control and study groups were comparable. Weight gain was within the expected range with advancement of pregnancy. Heart rate was increased in I and II trimesters with peak rise in III trimester. The difference between control group and study groups was statistically significant (p < 0.05).Systolic blood pressure was slightly decreased in all the trimesters as compared to control group which was statistically not significant. There was gradual increase in SBP from I to III trimesters. Diastolic blood pressure progressively decreased in I and II trimesters and then increased in III trimester. The difference in DBP between control group and I, II trimesters of pregnancy was significant (p<0.05).Systemic vascular resistance progressively decreased with advancement of pregnancy and difference was statistically significant (p <0.05) . Cardiac output is steadily increased in all trimesters of pregnancy with peak at 36 weeks and was statistically significant (p<0.05). It was due to increase in both heart rate and Stroke volume. Ejection fraction also increased in all trimesters.Conclusions: Present study shows significant functional changes in the cardiovascular dynamics during pregnancy. Doppler echocardiography provides an excellent noninvasive method for the evaluation and serial analysis of hemodynamic changes. These results will help in distinguishing abnormal echocardiographic changes from the normal physiologic changes of pregnancy. Therefore maternal echocardiography should be introduced into the antenatal management protocol, which will help to identify women at high risk to developing cardiovascular complications and there by early intervention.

Squeezing out the last 1 nanometer of water: A detailed nanomechanical study

In this study, we present a detailed analysis of the squeeze-out dynamics of nanoconfined water confined between two hydrophilic surfaces measured by small-amplitude dynamic atomic force microscopy (AFM). Explicitly considering the instantaneous tip-surface separation during squeezeout, we confirm the existence of an adsorbed molecular water layer on mica and at least two hydration layers. We also confirm the previous observation of a sharp transition in the viscoelastic response of the nanoconfined water as the compression rate is increased beyond a critical value (previously determined to be about 0.8 nm/s). We find that below the critical value, the tip passes smoothly through the molecular layers of the film, while above the critical speed, the tip encounters "pinning" at separations where the film is able to temporarily order. Pre-ordering of the film is accompanied by increased force fluctuations, which lead to increased damping preceding a peak in the film stiffness once ordering is completed. We analyze the data using both Kelvin-Voigt and Maxwell viscoelastic models. This provides a complementary picture of the viscoelastic response of the confined water film

Wolf Prize for Chemistry – 2019

Wolf Prize for Chemistry 201

Is James Watson right?

Is James Watson right