Karen Gleason, a chemical engineering professor at MIT, along with graduate student Miles Barr and others, showed that the technique could be used to print solar cells on a variety of delicate materials. One example is rice paper, which is used to make spring rolls in restaurants and usually dissolves in wet processes. Since the researchers’ technique is a dry, solvent-free process, the rice paper remains intact. The researchers also demonstrated the technique on plastic Saran wrap, which repels water and would normally be difficult to coat.The new method, called oxidative chemical vapor deposition (oCVD), involves spraying a vapor of a monomer and an oxidizing agent onto a substrate. The monomer and oxidizing agent polymerize when they meet and form PEDOT plastic. The plastic itself is conductive, but the conductivity can be further increased up to 1,000 times by controlling the substrate temperature so that small nanopores form, which can be laced with highly conductive silver particles.The printed solar cells can also withstand a great deal of bending and stretching with minimal effect on their properties. In tests, the researchers bent a printed plastic substrate to a radius of less than 5 mm more than 1,000 times, and found that its efficiency was still 99% of what is was before bending. The electrodes could also be bent and stretched, and still retained their conductivity. To further demonstrate the method’s robustness, Barr folded a piece of paper printed with solar cells into a paper airplane, and showed that the device still generated a current.MIT Professor Karen K. Gleason explains how graduate student Miles Barr folds a solar cell into a paper airplane. The research is part of the Eni-MIT Solar Frontiers Center. Video credit: MIT.As the researchers noted, paper is not typically considered a good substrate for photovoltaics because it’s not transparent. However, the ability to print solar cells at low-cost on flexible, stretchable materials could be very useful for making solar cells more widespread. Since the technique can also be used to print other electronic devices besides solar cells, it could be used for novel applications such as printing electronics on fabric and other flexible displays. To demonstrate how a new fabrication technique can print solar cells on extremely thin, flexible materials, researchers from MIT have patterned solar cells onto ordinary toilet paper. While toilet paper may be an unlikely substrate for practical solar cell applications, it illustrates the versatility of the technique for low-cost printing on a wide variety of materials. Explore further Xerox Develops Silver Ink for Cheap Printable Electronics After printing solar cells on a piece of paper, researchers folded the paper into an airplane to demonstrate that it could still generate current. Image credit: Karen Gleason, MIT. More information: via: IEEE Spectrum © 2010 PhysOrg.com Citation: Researchers print solar cells on toilet paper, other delicate materials (w/ Video) (2011, January 4) retrieved 18 August 2019 from https://phys.org/news/2011-01-solar-cells-toilet-paper-delicate.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
Kolkata: The body of an unidentified middle-aged man was found in a drainage channel at Sonarpur in South 24-Parganas on Sunday morning. Police said locals who went out on a morning walk noticed the body and informed the police. Policemen from the local police station went to the spot. After preliminary investigation, police found injury marks on his body.Police have initiated a probe in this connection and they are trying to identify the man. They have spoken to the locals to know whether they had seen the man earlier in the area. They are also trying to ascertain whether there is any foul play behind the incident or he received the injuries when he fell in the drainage channel. Police have contacted adjacent police stations to get the identity of the man.
Popular music has gradually become angrier and sadder over time, and the expression of joy has declined, a study has found. While music fans preferred joyful songs during the 1950s, modern music consumers are more interested in songs that express sadness or anger, researchers said. Data scientists at Lawrence Technological University in the US used quantitative analytics to study the change in lyrics of popular music over seven decades, from the 1950s to 2016. Also Read – Add new books to your shelf”The change in lyrics sentiments does not necessarily reflect what the musicians and songwriters wanted to express, but is more related to what music consumers wanted to listen to in each year,” said Lior Shamir, from Lawrence Technological University. Research analysed the lyrics of over 6,000 songs of the ‘Billboard Hot 100’ in each year. In the past the songs were ranked mainly by record sales, radio broadcasting, and jukebox plays, but in the more recent years it is based on several other popularity indicators such as streaming and social media to reflect the changes in music consumption. Also Read – Over 2 hours screen time daily will make your kids impulsiveThe tones expressed in each song were analysed by applying automatic quantitative sentiment analysis. Automatic sentiment analysis associates each word or phrase in the song with a set of tones that they express. The combination of the tones expressed by all words and phrases of the lyrics determines the sentiment of that song. The sentiments of all Billboard Hot 100 songs in each year are averaged, and the average of each year allows to measure whether the expression of that sentiment increased, decreased, or remained constant. The analysis showed that the expression of anger in popular music lyrics has increased gradually over time. Songs released during the mid 1950s were the least angry, and the anger expressed in lyrics has increased gradually until peaking in 2015. The analysis also revealed some variations. Songs released in the three years of 1982-1984 were less angry compared to any other period, except for the 1950s. In the mid 1990s, songs became angrier, and the increase in anger was sharper during that time in comparison to previous years. The expression of sadness, disgust and fear also increased over time, although the increase was milder compared to the increase in the expression of anger. Disgust increased gradually, but was lower in the early 1980s and higher in the mid and late 1990s. Popular music lyrics expressed more fear during the mid 1980s, and the fear decreased sharply in 1988. Another sharp increase in fear was observed in 1998 and 1999, with a sharp decrease in 2000. The study also showed that joy was a dominant tone in popular music lyrics during the late 1950s, but it decreased over time and became much milder in the recent years.