Buried screen-printed contacts for silicon solar cells

A Simple way to improve solar cell efficiency is to enhance the absorption of light and reduce the shading losses. One of the main objectives for the photovoltaic roadmap is the reduction of metalized area on the front side of solar cell by fin lines. Industrial solar cell production uses screen-printing of metal pastes with a limit in line width of 70-80 μm. This paper will show a combination of the technique of laser grooved buried contact (LGBC) and Screen-printing is able to improve in fine lines and higher aspect ratio. Laser grooving is a technique to bury the contact into the surface of silicon wafer. Metallization is normally done with electroless or electrolytic plating method, which a high cost. To decrease the relative cost, more complex manufacturing process was needed, therefore in this project the standard process of buried contact solar cells has been optimized in order to gain a laser grooved buried contact solar cell concept with less processing steps. The laser scribing process is set at the first step on raw mono-crystalline silicon wafer. And then the texturing etch; phosphorus diffusion and SiNx passivation process was needed once. While simultaneously optimizing the laser scribing process did to get better results on screen-printing process with fewer difficulties to fill the laser groove. This project has been done to make the whole production of buried contact solar cell with fewer steps and could present a cost effective opportunity to solar cell industries.

Evaluation of galling resistance for some selected combinations of tool steels/stainless steel sheet materials/lubricants using pin-on-disc testing

Stainless steels are well known to be prone to cold welding and material transfer in sliding contacts and therefore difficult to cold form unless certain precautions as discussed in this paper are taken. In the present study different combinations of tool steels/stainless steels/lubricants has been evaluated with respect to their galling resistance using pin-on-disc testing. The results show that a high galling resistance is favored by a high stainless steel sheet hardness and a blasted stainless steel sheet surface topography. The effect of type of lubricant was found to be more complex. For example, the chlorinated lubricants failed to prevent metal-to-metal contact on a brushed sheet surface but succeeded on a blasted sheet surface of the same stainless steel material. This is believed to be due to a protective tribofilm which is able to form on the blasted surface, but not on the brushed surface.

ICC-profilers funktionalitet vid byte av tryckfärgskvalitet

This degree theme work aims to evaluate the present ICC-profile and printing ink of Dalarnas Tidningar AB. The companyhas changed printing ink quality and wants to evaluate how the present ICC-profile work with the new printingink. Four different ICC-profiles were included in the comparison.One test printing was accomplished with two different separations. Two new ICC-profile was created, as a comparingmaterial. An densitometer was used to measure the technical parameters of the printing. IT8-charts and RGB-chartswas measured with spectrophotometer. La*b*-values, CMYK-values, graybalance curves, color deflections and colorgamuts was compared on screen and on the printed material.Materials from an earlier testprinting and evalution, made by Stora Enso Kvarnsveden AB 2003, was used to evaluatethe function of Dalarnas Tidningar AB´s ICC-profile with the present printing ink quality. The IT8-chart from todaystestprinting was oppened in a program for textediting to have access to La*b*- and CMYK values. The values from theearlier testprinting was supplied from Stora Enso Kvarnsveden AB.The result of this work shows that the ICC-profile from the company, compared with de other profiles, reproduce darkershadow regions which can make loss of details. An higher saturation is recieved in the red and yellow area while thegreen and blue area lose its intensity. The profile gave images which are some contrastless and with a flat reproduction.Today printing ink quality gives more saturation and intensity in the yellow and blue area compared with former printingink. The dark tone reproduces with decreased luminance, however.

Typografiska riktlinjer och textframställning för smartphones

Idag använder allt fler människor sina smartphones för att surfa och använda tjänster online. Detta innebär att en stor del text läses på små skärmar. Detta arbete handlar om hur text bäst utformas och struktureras för att enklast kunna läsas och uppfattas på en mobilskärm. Faktorer som berörs är typgrad, ljusrum, textlängd, teckensnittsklass, radlängd, bild i text och kontrastverkan. Arbetet utgår från en normativ, svensk person utan funktionsnedsättningar. Arbetet är grundat på litteratur, egna analyser, intervjuer med branschfolk, enkätundersökning och test med fokusgrupp. Resultatet blev att en text på smartphone bäst utformas med flera styckesindelningar i form av blankrader, med bilder där bilden tillför något i informativt syfte och textlängd baserat på ämneskategori. Bilden bör sättas ovanför brödtexten. Längre texter ska sättas med scrollfunktion. Kontrast har stor betydelse på mobiltelefoner, texter går bra att läsa även när de är satta negativt. Teckensnittsklass är enligt resultatet av denna rapport inte av betydelse. Både seriff och sanserif kan läsas utan problem på smartphones. Typgraden bör förstoras något i förhållande till telefonens default-inställningar. På grund av att text på skärm inte stödjer avstavningar rekommenderas korta ord där det är möjligt för att förhindra en allt för hackig högerkant.

Nationella läsförståelseprov – på papper eller på skärm? : En studie av elevresultat på digitala läsförståelseprov gentemot pappersbaserade prov

Due to the upcoming digitalization of the Swedish schools standardized national tests, the aim of this study is to compare the results of a reading comprehension test on paper versus on computer screen and to examine whether the results differ between boys and girls and between swedish and swedish as a second lanuague students, or not. Previous studies show inconclusive results, some show that students get higher results when taking a test on paper then on computer screen, some show that the results don’t differ between the two medias. In this study, the national test for course Svenska 1 (Swedish) and Svenska som andraspråk 1 (Swedish as a second language) from the autumn term 2011 was transformed into a digital test. 38 students in the 10th grade took the test and the results were then compared with the same students results on the following national test of the spring term 2016 which is given on paper. The results show that the scores between the digital test and the paperbased test don’t differ. The boys got equally lower scores than the girls in both the digital test and the paperbased test. The swedish as a second language students got lower scores than the swedish students. The results are discussed in relation to previous research by Ackerman and Lauterman (2012), Mangen, Walgermo and Brønnick (2013), Rasmusson (2014) , Pasquarella, Gottardo and Grant (2012) and Norman and Furnes (2016).