Impact of light scattering for efficiency enhancement in organic solar cells

Further efficiency enhancements in organic solar cells require a deeper understanding of the charge generation and transport in the cell as well as the employment of advanced light trapping mechanisms. Both electronic and optical device models for organic solar cells have been developed already in the past. This paper, however, for the first time presents a simulation tool that combines a state of the art driftdiffusion electrical model with a complex optical model able to simulate wave propagation in thin film optics but also ray-based light propagation in incoherent layers and scalar scattering. The combination of the light-scattering algorithm and this driftdiffusion model leads to a coupled opto-electronic cell model which represents a powerful design tool for cell characterization and optimization. This tool is then used to evaluate the gain of efficiency introduced by a light scattering interface made of a rough TCO in a bulk heterojunction (BHJ) solar cell. The results were found to be in good qualitative agreement with previously published experimental results

Dokspot : securely linking healthcare products with online instructions

Printed instructions for products get replaced more and more by digital versions that are made available over the internet. In safety-sensitive fields such as healthcare products, availability and integrity of these instructions is of highest importance. However, providing and managing instructions online opens the door to a wide range of potential attacks, which may negatively affect availability and integrity. In this paper, dokspot is presented, which is an internet-based service that aims at solving this problem by securely linking healthcare products with online instructions. The key to achieve this is a sophisticated security architecture and the focus of this paper is on the core components of this architecture. This includes a secure workflow to manage online instructions, which prevents, e.g., attacks by malicious insiders. Also, the traditionally monolithic web application architecture was split into role-based microservices, which provides protection even if parts of the system are compromised. Furthermore, digital signatures are utilized to continuously safeguard the lifecycle of online instructions to guarantee their genuineness and integrity. And finally, a passwordless signature scheme is introduced to hide inconvenient extra steps from the users while still maintaining security. Overall, this security architecture makes dokspot highly resistant to a wide range of attacks

Web content signing with service workers

Securing the communication between a web server and a browser is a fundamental task of securing the World Wide Web. Websites today rely heavily on HTTPS to set up secure connections. In recent years, several incidents undermined this trust and therefore the security of the HTTPS system. In this paper we introduce an approach allowing to secure JavaScript files in case a HTTPS connection between web server and browser is compromised. Our paper presents a solution to safeguard the user's browser so that it only processes content (e.g., JavaScript or HTML) that was genuinely provided by the web application service providers themselves. Our solution makes use of service workers, a recently proposed W3C Candidate Recommendation enabling applications to take advantage of persistent background processing, including hooks to enable bootstrapping of web applications while offline. It demonstrates how service workers are able to validate the integrity of JavaScript files within the client's browser and how service workers are used to detect and mitigate malicious JavaScript files

Simulations, measurements and optimization of OLEDs with scattering layer

A multi-scale optical model for organic light-emitting devices containing scattering layers is presented. This model describes the radiation of embedded oscillating dipoles and scattering from spherical particles. After successful model validation with experiments on a top-emitting white OLED, we show how this tool can be used for optimization with specific targets

Design tool for light scattering enhancement in OLEDs

A multi-scale optical model for organic light-emitting devices is presented. This model describes the radiation of oscillating dipoles embedded in real OLED structures including planarization layers, colour filters and scattering for enhanced light out-coupling. We show how the scattering properties impact the overall performances of white OLEDs