The Cyber Dialogue at the Crossroads: Why States Disagree on the Need for a New Cyber Treaty?

As evidenced by the preliminary results of work of the UN Open-ended Working Group on developments in the field of information and telecommunications in the context of international security, currently the states have different views towards legal regulation of cyberspace. A number of states (mostly Western) argue that the existing international law sufficiently addresses the relationships in the area, and they call on all interesting parties to express their views on how the law is applied, while other states, like Russia, China and Venezuela claim that there is a legal vacuum as to the regulation of cyberspace and propose starting to globally negotiate a new binding legal instrument. This paper explores the reasons for the states to insist on their views on the need for a new cyber treaty and demonstrates that the respective disagreement between states cannot be explained neither by a global interest in maintaining the state of legal uncertainty about the proper sources or rules, nor by the lack of choice of the parties to the debate regarding the tools to address such uncertainty. The authors argue that the explanation lies in the correlation between corresponding substantive and instrumental stances of both sides of the debate, since the states’ preferences regarding the appropriate rules can be more fully and effectively implemented within the respective instrumental solutions and such solutions provide their adherers with more tools to control the processes of their implementation

Study of optimization options for second generation solar cell materials by multilevel modeling

Theoretical analysis of optimization options for the properties of CdTe absorber layer is an important task for increasing the efficiency of CdTe/CdS heterojunction based thin-film solar cells. Properties of the materials (e.g. the density of free carriers) often depend essentially on the parameters of the deposition process and subsequent treatment which determine the defect composition of the material. In this work a model based on the lattice kinetic Monte-Carlo method is developed to describe the process of CdTe deposition as a function of temperature and Cd and Te fluxes. To determine the effect of the treatment conditions on CdTe conductivity, we developed a quasichemical model based on the electrical neutrality equation for point defect concentrations that are described by defect formation reaction constants. Parameters obtained from the first-principles density functional calculations were used for developing the models. The developed deposition model correctly describes the transition from evaporation to precipitation as well as the increased evaporation rates in excess of Cd. To explain the observed electrical properties of CdTe after Cl-treatment, we complemented the quasichemical defect model by a deep acceptor complex defect that allowed us to describe both the high-temperature dependence of conductivity on the Cd pressure and the dependence of resistivity on Cl concentration at room temperature

A Search for New Back Contacts for CdTe Solar Cells

There is widespread interest in reaching the practical efficiency of cadmium telluride (CdTe) thin-film solar cells, which suffer from significant open-circuit voltage loss due to high surface recombination velocity and Schottky barrier at the back contact. Here, we focus on back contacts in the superstrate configuration with the goal of finding new materials, that can provide improved passivation, electron reflection and hole transport properties compared to the commonly used material, ZnTe. We performed a computational search among 229 binary and ternary tetrahedrally-bonded structures using first-principles methods and transport models to evaluate critical materials design criteria, including phase stability, electronic structure, hole transport, band alignments, and p-type dopability. Through this search, we have identified several candidate materials and their alloys (AlAs, AgAlTe2, ZnGeP2, ZnSiAs2, CuAlTe2) that exhibit promising properties for back contacts. We hope these new material recommendations and associated guidelines will inspire new directions in hole transport layer design for CdTe solar cells

Predicting the Operational Stability of Phosphorescent OLED Host Molecules from First Principles: A Case Study

Low operational stability is the main limiting factor for commercialization of the blue phosphorescent organic light emitting diodes (PhOLEDs). The high energy and long lifetime of triplet excitons in blue PhOLEDs makes them more prone to degradation. Degradation of the host molecules in the emitting layer of PhOLEDs is one of the possible mechanisms leading to the luminosity loss in the course of device operation. Although possible degradation mechanisms are proposed in the literature, predicting the degradation kinetics is not straightforward because the evolution of excited states should be accurately described. We propose a computational scheme to assess the operational stability of PhOLED host materials. Our protocol relies on the usage of the multireference CASSCF/XMCQDPT2 method. In the present work we consider the degradation of four prototypical blue PhOLED host molecules in the charged and excited states as well as the degradation induced by exciton–polaron and exciton–exciton annihilation processes with the focus on breaking of exocyclic C–C or C–N bonds and triazine ring fission. By analyzing the calculated activation energies for different mechanisms we found the least stable states and the most probable dissociation pathways. On the basis of our computations, we derived a stability series for the studied molecules and determine the structural features that provide higher stability with respect to the unimolecular dissociation

{CdTe}-based thin film photovoltaics: Recent advances, current challenges and future prospects

Cadmium telluride (CdTe)-based cells have emerged as the leading commercialized thin film photovoltaic technology and has intrinsically better temperature co-efficients, energy yield, and degradation rates than Si technologies. More than 30 GW peak (GWp) of CdTe-based modules are installed worldwide, multiple com-panies are in production, modules are shipping at up to 18.6% efficiency, and lab cell efficiency is above 22%. We review developments in the science and technology that have occurred over approximately the past decade. These achievements were enabled by manufacturing innovations and scaling module production, as well as maximizing photocurrent through window layer optimization and alloyed CdSexTe1-x (CST) absorbers. Improved chlorine passivation processes, film microstructure, and serendipitous Se defect passivation significantly increased minority carrier lifetime. Efficiencies >22% have been realized for both Cu and As doped CST-based cells. The path to further efficiency gains hinges primarily on increasing open circuit voltage (Voc) and fill factor (FF) through innovations in materials, fabrication methods, and device stacks. Replacing the longstanding Cu doping with As doping is resulting in better module stability and is being translated to large-scale production. To realize 25% efficiency and >1 V Voc, research and development is needed to increase the minority carrier lifetime beyond 100 ns, reduce grain boundary and interface recombination, and tailor band diagrams at the front and back interfaces. Many of these goals have been realized separately however combining them together using scalable manufacturing approaches has been elusive to date. We review these achievements and outstanding opportunities for this remarkable photovoltaic technology

CdTe-based thin film photovoltaics: recent advances, current challenges and future prospects

Cadmium telluride (CdTe)-based cells have emerged as the leading commercialized thin film photovoltaic technology and has intrinsically better temperature coefficients, energy yield, and degradation rates than Si technologies. More than 30 GW peak (GWp) of CdTe-based modules are installed worldwide, multiple companies are in production, modules are shipping at up to 18.6% efficiency, and lab cell efficiency is above 22%. We review developments in the science and technology that have occurred over approximately the past decade. These achievements were enabled by manufacturing innovations and scaling module production, as well as maximizing photocurrent through window layer optimization and alloyed CdSexTe1-x (CST) absorbers. Improved chlorine passivation processes, film microstructure, and serendipitous Se defect passivation significantly increased minority carrier lifetime. Efficiencies >22% have been realized for both Cu and As doped CST-based cells. The path to further efficiency gains hinges primarily on increasing open circuit voltage (Voc) and fill factor (FF) through innovations in materials, fabrication methods, and device stacks. Replacing the longstanding Cu doping with As doping is resulting in better module stability and is being translated to large-scale production. To realize 25% efficiency and >1 V Voc, research and development is needed to increase the minority carrier lifetime beyond 100 ns, reduce grain boundary and interface recombination, and tailor band diagrams at the front and back interfaces. Many of these goals have been realized separately however combining them together using scalable manufacturing approaches has been elusive to date. We review these achievements and outstanding opportunities for this remarkable photovoltaic technology.</p