Within this work, both the performance and reliability of industrial p-type monocrystalline solar cells with dielectrically passivated rear side and corresponding modules are investigated. Results of the mass production of Q.ANTUM solar cells at Hanwha Q CELLS on boron-doped p-type Czochralski-grown silicon (Cz-Si) substrates are presented, exceeding 21.5 % average conversion efficiency. Without power-enhancing measures such as the use of half cells, multi-wire approaches or light-capturing ribbons, essentially all currently (as of March 2017) produced Cz-Si Q.ANTUM solar modules exhibit output powers of > 300 Wp with 60 full 4-busbar cells. In terms of reliability, light-induced degradation (LID) is investigated in detail, with conditions relevant for the activation of, both, the boron-oxygen (BO) defect, and, so-called "Light and Elevated Temperature Induced Degradation" (LeTID). While the formation of the BO defect has been considered the most prominent LID mechanism in boron-doped p-type Cz-Si, LeTID has so far been discussed mainly as a potential issue for passivated emitter and rear cells (PERC) on multicrystalline silicon (mc-Si) substrates. This work shows that, if not adequately suppressed, LeTID can also occur in p-type Cz-Si PERC with a degradation in output power of up to > 6 %, which cannot be suppressed in a straightforward manner by conventional processing steps to permanently deactivate the BO defect. In contrast to conventional PERC, Hanwha Q CELLS Q.ANTUM technology is shown to reliably suppress, both, LID due to BO defect formation, and, LeTID in modules manufactured from, both, p-type mc-Si and Cz-Si substrates.

Light-induced degradation (LID) has been identified to be a critical issue for the long-term stability of solar cells and modules from boron-doped silicon substrates. Besides the well-known LID of excess charge carrier lifetime within Czochralski-grown silicon substrates induced by the activation of the boron-oxygen complex, significant performance degradation has been observed also for certain multicystalline silicon (mc-Si) solar cells and modules. This degradation is significantly more pronounced at elevated temperatures and, therefore, referred to as LeTID for “Light and elevated Temperature Induced Degradation”. If not controlled, LeTID can induce a decrease of conversion efficiency by more than 10 %rel, particularly for solar cells with dielectrically passivated surfaces. This paper gives an overview on some key characteristics of LeTID and shows that LeTID can be suppressed during cell processing by Hanwha Q CELLS’ Q.ANTUM technology. The formation rate of LeTID is shown to increase with excess carrier concentration and temperature, and the impact of different dielectric surface passivation layers on LeTID is discussed, assigning a significant part of LeTID to a bulk defect. Furthermore, substrates from several high-performance mc-Si wafer producers are shown to be prone to severe LeTID, if not suppressed adequately during cell processing. Hence, to date no solution for LeTID on substrate side is widely available to our knowledge. In order to enable the efficiency and corresponding cost saving potential of dielectrically passivated compared with standard aluminium back-surface field mc-Si solar cells, LeTID needs to be suppressed by adapted cell processing.

In this work the performance stability of rear side passivated mc-Si solar cells and modules under carrier injection at different temperatures is investigated. Severe degradation levels of above 10% can be detected which cannot be explained by B-O complex formation or FeB pair dissociation. A high statistic of cells and modules degraded in lab and outdoor using material from different suppliers confirm the relevance of this new effect. LeTID (Light and elevated Temperature Induced Degradation) is a mc-Si bulk phenomena leading to a highly injection dependent degradation and features a regeneration phase after degradation. Characteristics of LeTID as a function of temperature and injection level are presented and a comparison between laboratory and outdoor tests is drawn. The time constant of this degradation mechanism accelerates with increasing temperature, however, the time span for degradation and regeneration of thousands of hours at relevant temperatures between 60-85°C demands for a solution on wafer material or processing side. LeTID can be significantly reduced by adapting the cell process and processing sequence.

In this paper we present the latest R&D results of Q.Cells' high-efficiency solar cell and module concept Q.antum that is currently transferred into mass production. The current work is focused on solar cells and modules produced in our Reiner-Lemoine Research Center. Our optimized rear passivation concept in combination with innovations on the front side of the solar cell resulted in record module efficiencies of 18.5% based on isotropic textured multi-Si substrates. In addition we adopt our Q.antum process on mono-cast (mono-like-multi) Si wafer. These wafers were disposed to an alkaline texturing process and converted into a solar module with record output powers of 283 W. By following the idea of an evolutional cell development a symmetrical passivation that means having the same passivation material on front and rear side could displace cells with different passivation materials on front and rear side. On basis of diffused and non-diffused lifetime test samples we investigate in particular the saturation current density to evaluate the open circuit voltage potential and consequently the feasibility of the evaluated dielectric films for the application as symmetrical passivation scheme. These results were extended by analyzing the implied J-V characteristics to get insights into the feasibility of the investigated passivation schemes.

We study the dependence of solar cell parameters on base resistivity for double-side contacted n-type rear junction solar cells with boron emitter and local rear contacts. Experimental data for solar cells processed on n-type Cz Si wafers with base resistivities ranging from 2Ω·cm to 16Ω cm are compared to device simulations for the respective resistivity range. Our experimental data show the typical strong increase of efficiency with base resistivity in the range of 2 - 5Ω cm and at about 10Ω cm a saturation of efficiency with base resistivity sets in [1–4].Comparison of experimental and simulation results reveal that our experimental findings are closely reproduced assuming a constant bulk lifetime after solar cell processing. Furthermore the results of this study were implemented in an optimized solar cell process. With 14Ω cm n-type Cz as base material solar cell efficiencies of up to 20.9% on 243.4cm2 (total area) were achieved which was confirmed by Fraunhofer ISE CalLab.

In this paper we report on a pilot production of multi-crystalline p-type Si cells in the Reiner-Lemoine Research Center at Q-Cells SE. The cells are double-side contacted and feature a lowly doped emitter, a fineline-printed Ag grid in combination with plating as front metallisation and a dielectric passivated rear with local contacts. Using upgraded metallurgical grade (UMG) and Poly Si we report on median cell efficiencies>18% over a whole brick and independently conformed top efficiencies of up to 18.35% (UMG) and 18.45% (Poly) on large cell areas (243cm2). Furthermore, with a module efficiency of 17.84% on 1.5 m2 we report on a new world record on multi-crystalline large area modules (60 cells). To our knowledge, these are the highest efficiencies on cell level based on UMG Si and on multi-crystalline modules reported so far.

Nanostructured oxidic thin films are of interest due to their applicability in many different fields like filtration technology, catalysis, biomaterials and self purification. In this paper, we present sol–gel derived SiO2 and SiO2–TiO2 thin films with a new fingerprint-like nanostructure. The films were produced by dip-coating glass slides into the sol and a temperature treatment at 500 and 600°C. The characterization methods were FEGSEM and AFM. The dimensions of the nanostructured surface pattern were calculated from the AFM data with the power spectral density method.

Postoperative implant-associated infection is still an unresolved and serious complication in modern surgery. Antibacterial and biocompatible surfaces could both reduce infection rates and promote tissue integration. In this respect, a comparative study of the antibacterial as well as the biocompatible potential of different metal ions in vitro is presented. The assays used were growth inhibition tests with different metal salts carried out with tissue cells and bacteria under corresponding culture conditions. Additionally, in vitro tests in direct surface contact with tissue cells and bacteria onto a novel copper containing sol-gel derived titanium dioxide coating (Cu-TiO2) and a fourfold Cu-TiO2 coating were performed. The values were compared to a non-filled titanium dioxide coating and standard Ti6Al4V alloy. SEM-investigations were performed to approve the results of the in vitro tests. Among Ag+, Zn2+, Co2+, Al3+ and Hg2+, the growth inhibition tests revealed an outstanding position of copper ions as antibacterial but nevertheless bio-tolerant additive. These results were affirmed by the cell tests in direct surface contact and SEM-investigations, where best cell growth was found on the Cu-TiO2 coatings. Highest antibacterial properties with a tolerable cytocompatibility could be observed on the fourfold Cu-TiO2 coatings. Consequently, surfaces with custom-tailored antibacterial properties may be established and could be of particular interest in revision and tumor arthroplasty.

The porosity of a hydroxyapatite ceramic was tailored by transferring polymeric pore models into ceramic forms via the slip casting technique. The rheological properties of the hydroxyapatite slurries play an important role in facilitating the casting operation. Aqueous hydroxyapatite slurries with a high solids content were fabricated. The optimised slurry with 60 wt% hydroxyapatite had a slight shear thickening flow behaviour and a low viscosity. The resulting porous ceramic could be reasonably handled and had a very high interconnecting porosity of 91 - 96 vol%. The pore size varied between 300 and 800 mum. The density value of the bulk hydroxyapatite ceramic covered the range between 94 and 96% th.d.. The characteristics of the porous ceramics could be varied between high and undirected porosity and low porosity with defined pore channels in the three dimensional directions.

The porosity of a hydroxyapatite ceramic was tailored by transfe rring polymeric pore models into ceramic forms via the slip casting technique. The rheolog ical properties of the hydroxyapatite slurries play an important role in facilitating t he casting operation. The optimised slurry with a solids content of 60 wt% hydroxyapatite had a slight s hear thickening flow behaviour and a low viscosity. Via impregnating of polymeric pore models and dip coating of pol ymeric foams ceramic green bodies were fabricated. After sintering at 1250 °C the polymer was burnt out and a porous ceramic was achieved. This porous ceramic could be reasonably handl ed and had a very high interconnecting porosity of 91 – 96 vol%. The pore size varied between 300 and 800 μm. The density value of the bulk hydroxyapatite ceramic covered the range bet w en 94 and 96 % th.d.. The characteristics of the porous ceramics could be varied between high and undirected porosity on the one hand, and lower porosity with defined pore channels in the three dimensiona l directions on the other hand. Introduction There is an increasing clinical requirement for bone graft mate rial, because there are many possible applications such as revision hip surgery, defect filling after e.g . a tumor surgery, or reconstructive orthopaedic surgery. As hydroxyapatite closely resembles the miner al phase of natural bone and is highly biocompatible, it is among other calcium phosphates widely used a s bone substitute material [1]. Synthetic hydroxyapatite can be reproducibly processed, and additionally, pr ovides no danger of infections. A large number of research activities has been dealing with the fabrication of synthetic hydroxyapatite ceramics [2, 3, 4, 5]. In this work the porosity of a hydroxyapatite ceramic was tailore d, so that the resulting bone substitute material is adapted to the requirements of the implanta tion site. The tailoring of the pore structure was carried out by using commercially available polyme ric foams and polymeric pore models, which were produced via rapid prototyping. These polymeric models w ere coated or impregnated with hydroxyapatite using the slip casting technique. This work is part of the research network ForTePro (Bayerische F orschungsstiftung, Germany), in which scientists of different research areas, particularly medical doctors, develop individually adapted implants for bone and cartilage defects, which will be cultivated with the pat ients own cells. Materials and Methods For producing the slurry the commercially available hydroxyapatite powder from Merck, Germany, was used. The specific surface area was characterised by the BET method (model Gemini 2370, micromeritics, Germany). The mean particle size d 50 was determined with a laser particle size analyser (model Granulomètre 850, Cilas Alcatel, France). The powder as slowly added to distilled water under constant stirring. The dispersant agent was a solution of a natrium salt of an acrylic acid copolymer. Additionally, a surfactant for improved wett ability and a binder were used. Key Engineering Materials Online: 2003-12-15 ISSN: 1662-9795, Vols. 254-256, pp 977-980 doi:10.4028/www.scientific.net/KEM.254-256.977 © 2004 Trans Tech Publications Ltd, Switzerland All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications Ltd, www.scientific.net. (Semanticscholar.org-13/03/20,19:47:28) Title of Publication (to be inserted by the publisher) The viscosity of the slurries was measured in a rotational rheome t r (model Rheolab MC 100, Physica, Germany) with shear rates from 0 to 800 1/s. Porous hydroxyapatite ceramic was fabricated by impregnating or c oating polymeric pore models, e.g. rapid prototyping models or polyurethane (PU) foams (KURETA , Germany) of different pore sizes 30, 35 and 45 ppi (pores per inch), with the hydroxyapati te slurry. The resulting structure was dried and then heat-treated at 1250 °C. The pyrolyses beha viour of the rapid prototyping models and PU foams was characterised by thermo-gravime tric asurements (model STA 409, Netzsch, Germany). The porosity was determined with a helium pyknometer (model Accu-Pyk 1330, micromeritics, Germany) and a scanning electron microscope (model Jeol 6400, Jeol, Japan) . To analyse the phase composition of the ceramic a X-ray diffractometer (model XRD 3000P, Seifert, Ge rmany) was used. For comparison dense hydroxyapatite cylinders were prepared by casti ng the slurry into plaster moulds. After drying the resulting green bodies were sintered at 1250 °C. Green density was determined by geometrical weight-volume evaluation. Sintering density was measured by the Archimedes’ method. The shrinkage and sintering start temperature w er determined with a dilatometer (model 402 E/7, Netzsch, Germany). Results and Discussion The commercially available hydroxyapatite powder has a specific surface area of 64 m2/g. Using this powder only slurries with a relatively low solids content of 35 wt% and a high viscosity could be prepared. After calcination of the powder at 900 °C the specific sur ace area was reduced to 12.5 m2/g. Using the calcined powder slurries with a high solids content from 55 to 65 wt% were produced. The flow behaviour of these slurries is affected by the chara cter and the amount of the dispersant (Fig. 1). Other additives like the binder can change the vis cosity as well, but to a minor degree. The binder used in this work reduced the viscosity. The slurries showed a shear thickening flow behaviour, whereas the viscosity increased with rising solids c ontent. As an optimum between the two desired properties low viscosity and high solids content, slurri es with a solids content of 60 wt% were chosen for further experiments. The mean particle diam eter in the stabilized slurries is approximately 2.8 – 3.2 μm. No sedimentation occurred for several hours. 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300

Verfahren zur Herstellung einer Titanoxid-Beschichtung auf einem Implantat mit den Schritten: a) Versetzen einer Zubereitung, enthaltend ein organisches Losungsmittel, einen metallorganischen Titanoxid-Precursor, mit Metallsalzen und/oder metallorganischen Verbindungen, um Metallionen homogen in der Zubereitung zu verteilen, die eine antimikrobielle oder antibakterielle Wirkung zeigen, b) Aufbringen der unter a) hergestellten Zubereitung auf ein Implantat, c) Trocknen der aufgebrachten Beschichtung.

The biological response of an organism to an implant can be influenced by structuring and/or functionalisation of the implant surface. The goal of our study is to improve the osseointegration of orthopaedic endoprothesis by coating metal substrates with dense or nanoporous titania layers combined with biofunctionalisation of the surface with peptides and proteins.The sol-gel method is used to produce titania coatings on medical relevant substrates such as titanium or titanium alloys. Control of the educt ratios and the processing, like drying the specimens in air (xerogel) or supercritical drying in an autoclave unit (aerogel), results in dense or nanoporous titania films. Pore diameters can be adjusted between 10 and 120 nanometers. A remarkable characteristic of the coatings is the high number of surface hydroxy functionalities even after calcination. These reactive groups give ideal conditions for the biofunctionalisation. The immobilisation of biological active substances is carried out by successive covalent silanisation with an aminosilane using a dicarbonic acid as a spacer molecule, and binding of peptides to the spacers. Biocompatibility and cytotoxicity of the materials were tested with cell culture assays.