Ready cells for large scale systems

For emerging photovoltaic technologies to become commercially and technically viable, it is important to understand how performance in the laboratory translates to the feld. A new study analyses the yearly changes in the energy yield of perovskite solar cells under simulated realistic temperature and irradiance conditions

Impact of Solar Cell Cracks Caused During Potential-Induced Degradation (PID) Tests

Potential-induced degradation (PID) of photovoltaic (PV) modules is one of the most severe types of degradation in modern modules, where power losses depend on the strength of the electric field, the temperature and relative humidity, and the PV module materials. Understanding how module defects impact PID is key to reducing the issue. This work investigates the impact of cracks and fractural defects in solar cells and their impact on PID. We have tested using electroluminescence (EL) imaging how solar cells with varying levels of cracks/defects impact PID and our results indicate that such defects have a sizeable influence on the PID. We also confirmed the strong relationship between the size of the initial defect/crack and the presence of hotspots. As the crack (dark) area increased, there was a further increase in the cell's temperature under standard test conditions (STCs). In this work, it is observed that minor cracks in solar cells have no considerable PID effect for the solar cells providing some reassurance that quality control can reduce this degradation pathway

Alternative selection of processing additives to enhance the lifetime of OPVs

The use of processing additives is known to accelerate the degradation of Organic Photovoltaics (OPVs) and therefore, this paper studies the impact of selecting alternative processing additives for PCPDTBT:PC71BM solar cells in order to improve the stability. The use of naphthalene-based processing additives has been undertaken, which is shown to reduce the initial power conversion efficiency by 23%-42%, primarily due to a decrease in the short-circuit current density, but also fill factor. However, the stability is greatly enhanced by using such additives, with the long term stability (T50%) enhanced by a factor of four. The results show that there is a trade-off between initial performance and stability to consider when selecting the initial process additives. XPS studies have provided some insight into the decreased degradation and show that using 1-chloronaphthalene (ClN) leads to reduced morphology changes and reduced oxidation of the thiophene-ring within the PCPDTBT backbone.HW would like to thank Bangor University for his 125 scholarship enabling his PhD study. JK would like to thank Sêr Cymru national research network in Advanced Engineering and Materials and the Newton Research Collaboration Programme scheme through the Royal Academy for Engineerin

Chemical and device degradation in PCPDTBT: PCBM solar cells using XPS and ToF-SIMS

Analysis of the degradation routes for PCPDTBT-based solar cells under illumination and in the presence of air have been conducted using a combination of X-ray Photoelectron Spectroscopy (XPS), Time-Of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) and solar cell device data. After ageing, XPS studies show that PCPDTBT appears as an oxygen-containing polymer, with data indicating that a break-up in the aromatic rings, formation of sulphates at the thiophene ring, chain scission in the polymer backbone and also loss of side chains. XPS studies on active layers blends of PCPDTBT and PCBM also show significant changes in the vertical composition during ageing, with increased enrichment of PCPDTBT observed at the top surface and that the use of a processing additive (ODT) has a negative impact on the morphological stability. TOF-SIMS has been used to study electrode degradation during ageing experiments leads to migration of indium and tin ions into the active layer in non-inverted devices, but is eliminated for inverted devices.RAEng and EC financial support and Prof TJ Lewis (Bangor) for technical suppor

Improving the Sustainability of Printed Circuit Boards Through Additive Printing

A life-cycle assessment (LCA) was performed on Printed Circuit Boards (PCB) made using the traditional manufacturing approach with FR-4 substrates. LCA is vital as it allows for comparison of products in order to design it so that it has the lowest impact on the environment. The scope was cradle to grave, including embodied impacts, transportation, energy used during manufacturing, waste material generated and disposal. The impact of different processing steps were considered, all scored using the ReCiPe Endpoint. Results show that consideration should be given to PCB design, including number of layers used in multilayer boards. Furthermore, the study investigated the impact of changing the manufacturing methodology by considering an additive printed circuit board. A significant reduction in environmental impact is seen by moving to either polymeric or paper based substrates

Optimization of a continuous hot embossing process for fabrication of micropyramid structures in thermoplastic sheets

Reported is the manufacture and optimization of inverted micropyramid cavity structures into thermoplastic sheets using roll-to-roll (R2R) embossing. To manufacture the master, an ultraprecision diamond machining method was applied to create seamless surface structures into a copper-coated hot embossing roller. Using the hot embossing process, the roller features were successfully transferred to 2 mm thick polymethyl methacrylate (PMMA) sheets. Optimization of the R2R control process variables was conducted using Taguchi's numerical methods, which showed the importance of the roller temperature for a successful pattern transfer. The work presents a novel fabrication technique that allows microstructures to be manufactured into thick PMMA sheets in a continuous process

Development of a Wireless Sensor Node for Building Information Management Systems

An increasing number of internet of things (IoT) devices are being deployed long term and therefore need to be self-powered in order to reduce maintenance costs. This paper reports on the design and implementation of a low power wireless sensor node for use in a building information management system powered by an organic solar module. Detailed analysis of the power requirements of the various sensors and the methods used to reduce the power consumption are given. The suitability of organic photovoltaic modules for indoor energy harvesting is examined. Early results from the deployment of these modules are shown

Development of an Improved Computer Model for Organic Photovoltaic Cells

This paper reports on an improved diode approximation-based model for PVs which is tested on three different organic PV (OPV) modules: AgGrid, AgNW and Carbon OPV. The model can emulate the electrical characteristics of the three cells accurately, facilitating the deployment in system models. Analytical I-V and P-V curves obtained with the model are compared with outdoor test data and demonstrate high correlation