Een nieuwe atoomlaagdepositieproces voor efficiëntere zonnecellen

De prijs van zonnecellen is de laatste jaren aanzienlijk gedaald, waardoor geïnstalleerde zonnecellen tegenwoordig binnen afzienbare tijd zijn terugverdiend. Echter, om vooruitgang in het rendement en de kostprijs te kunnen blijven boeken zijn nieuwe technieken en materialen nodig. Een techniek die interessante mogelijkheden biedt voor de zonnecelindustrie is atoomlaagdepositie (ALD). Deze techniek wordt gebruikt om zeer dunne lagen, van slechts enkele nanometers dik, te ‘deponeren’ of ‘aan te groeien’. Op deze manier kunnen deze ‘films’ met zeer grote controle over de dikte én de ateriaaleigenschappen aangebracht worden. In dit artikel beschrijven we hoe we een nieuw ALDproces voor molybdeenoxide (MoOx) hebben ontwikkeld en hoe dit proces mogelijk gebruikt kan worden om het rendement te verhogen van zonnecellen van het zogenaamde type ‘silicium-heterojunctie’. We laten zien dat het materiaal zeer puur en transparant is en dat we goede prestaties kunnen verwachten voor een zonnecel met MoOx

Low Temperature Atomic Layer Deposited Magnesium Oxide as a Passivating Electron Contact for c Si Based Solar Cells

In this article, we explore magnesium oxide MgO as electron selective contact layer in silicon heterojunction solar cells. We report on the successful deposition of MgO layers by atomic layer deposition at low temperatures amp; 8804;200 C using bis ethylcyclopentadienyl magnesium Mg CpEt 2 and H2O as precursors. Depositions were carried out on bare crystalline silicon c Si wafers and c Si wafers with an intrinsic amorphous hydrogenated silicon i aSi H passivation layer. The resulting interfacial properties, surface passivation quality, and contact resistivity were investigated. Upon initial deposition of MgO on an i aSi H c Si stack, the c Si surface passivation degrades drastically. However, with an additional annealing step of 5 min at 200 250 C, it is possible to reverse the degradation and even to achieve charge carrier lifetimes in excess of those achieved with an i aSi H alone. Furthermore, we show that MgO forms an ohmic contact with both MgO i aSi H c Si and MgO c Si stacks, and we demonstrate solar cells using both types of stacks as electron contact layer

Depositie van polykristallijn silicium voor dunne-film zonnecellen

In dit artikel beschrijven we de succesvolle depositie door middel van een expanderend thermisch plasma (ETP) van polykristallijn silicium (poly-Si), een aantrekkkelijk materiaal voor dunne-film zonnencellen

Treatment of early-stage breast cancer with percutaneous thermal ablation, an open-label randomised phase 2 screening trial:rationale and design of the THERMAC trial

INTRODUCTION: Breast cancer is the most frequently diagnosed malignancy worldwide but almost half of the patients have an excellent prognosis with a 5-year survival rate of 98%–99%. These patients could potentially be treated with thermal ablation to avoid surgical excision, reduce treatment-related morbidity and increase patients’ quality of life without jeopardising treatment effectiveness. Previous studies showed highest complete ablation rates for radiofrequency, microwave and cryoablation. However, due to heterogeneity among studies, it is unknown which of these three techniques should be selected for a phase 3 comparative study. METHODS AND ANALYSIS: The aim of this phase 2 screening trial is to determine the efficacy rate of radiofrequency, microwave and cryoablation with the intention to select one treatment for further testing in a phase 3 trial. Additionally, exploratory data are obtained for the phase 3 trial. The design is a multicentre open-label randomised phase 2 screening trial. Patients with unifocal, invasive breast cancer with a maximum diameter of 2 cm without lymph node or distant metastases are included. Triple negative, Bloom-Richardson grade 3 tumours and patients with an indication for neoadjuvant chemotherapy will be excluded. Included patients will be allocated to receive one of the three thermal ablation techniques. Three months later surgical excision will be performed to determine the efficacy of thermal ablation. Treatment efficacy in terms of complete ablation rate will be assessed with CK 8/18 and H&E staining. Secondary outcomes include feasibility of the techniques in an outpatient setting, accuracy of MRI for complete ablation, patient satisfaction, adverse events, side effects, cosmetic outcome, system usability and immune response. ETHICS AND DISSEMINATION: This study protocol was approved by Medical Research Ethics Committee of the Erasmus Medical Center, Rotterdam, the Netherlands. Study results will be submitted for publication in peer-reviewed journals. TRIAL REGISTRATION NUMBER: NL9205 (www.trialregister.nl); Pre-results

Textured interfaces in monolithic perovskite silicon tandem solar cells advanced light management for improved efficiency and energy yield

Efficient light management in monolithic perovskite silicon tandem solar cells is one of the prerequisites for achieving high power conversion efficiencies PCEs . Textured silicon wafers can be utilized for light management, however, this is typically not compatible with perovskite solution processing. Here, we instead employ a textured light management LM foil on the front side of a tandem solar cell processed on a wafer with planar front side and textured back side. This way the PCE of monolithic, 2 terminal perovskite silicon heterojunction tandem solar cells is significantly improved from 23.4 to 25.5 . Furthermore, we validate an advanced numerical model for our fabricated device and use it to optically optimize a number of device designs with textures at different interface with respect to the PCE and energy yield. These simulations predict a slightly lower optimal bandgap of the perovskite top cell in a textured device as compared to a flat one and demonstrate strong interdependency between the bandgap and the texture position in the monolithic stack. We estimate the PCE potential for the best performing both side textured device to be 32.5 for a perovskite bandgap of 1.66 eV. Furthermore, the results show that under perpendicular illumination conditions, for optimized designs, the LM foil on top of the cell performs only slightly better than a flat anti reflective coating. However, under diffuse illumination, the benefits of the LM foil are much greater. Finally, we calculate the energy yield for the different device designs, based on true weather data for three different locations throughout the year, taking direct as well as diffuse illumination fully into account. The results further confirm the benefits of front side texture, even more for BIPV applications. Overall, devices built on a both side textured silicon wafer perform best. However, we show that devices with textured LM foils on the cell s front side are a highly efficient alternativ

Atomic Layer Deposition for crystalline silicon solar cells:Innovate at the nanoscale, deploy at the gigawatt scale

Over the last decade, solar energy has boomed with an annual production already exceeding 140 gigawatts. This market is dominated by crystalline silicon cells, for which innovations at the nanoscale have been key to enabling higher cell efficiency at low cost. Atomic layer deposition is very much present in the research for nanolayer innovations, as ALD provides a platform to prepare these nanolayers with atomic-level precision and control. Meanwhile, nanoscale ALD layers are also deployed at the gigawatt scale, with Dutch companies and universities playing a pioneering role in scaling up. In this perspective article, I will show where ALD nanolayers can be found in the solar cells you buy today, and which future innovations are expected