Efficient Light Management by Textured Nanoimprinted Layers for Perovskite Solar Cells

Inorganic organic perovskites like methylammonium lead iodide have proven to be an effective class of materials for fabricating efficient solar cells. To improve their performance, light management techniques using textured surfaces, similar to those used in established solar cell technologies, should be considered. Here, we apply a light management foil created by UV nanoimprint lithography on the glass side of an inverted p i n perovskite solar cell with 16.3 efficiency. The obtained 1 mA cm 2 increase in the short circuit current density translates to a relative improvement in cell performance of 5 , which results in a power conversion efficiency of 17.1 . Optical 3D simulations based on experimentally obtained parameters were used to support the experimental findings. A good match between the simulated and experimental data was obtained, validating the model. Optical simulations reveal that the main improvement in device performance is due to a reduction in total reflection and that relative improvement in the short circuit current density of up to 10 is possible for large area devices. Therefore, our results present the potential of light management foils for improving the device performance of perovskite solar cells and pave the way for further use of optical simulations in the field of perovskite solar cell

Three Terminal Perovskite Silicon Tandem Solar Cells with Top and Interdigitated Rear Contacts

We present a three terminal 3T tandem approachfor the interconnection of a perovskite top cell with aninterdigitated back contact IBC silicon heterojunction SHJ bottom cell. The general viability of our cell design is verified withdrift diffusion simulations indicating efficient charge carriertransport throughout the whole device and an efficiency potentialof amp; 8776;27 by using readily available absorber and contact materials.Our experimental proof of concept device reaches a combinedPCE of 17.1 when both subcells are operating at their individualmaximum power point. To emulate different operation conditions,the current amp; 8722;voltage characteristics of both cells were obtained bymeasuring one subcell while the other cell was set to afixed biasvoltage. Only a slight mutual dependence of both subcells wasfound. As determined by electrical simulations, this dependence likely stems from the resistance of the electron contact on the cell srear side, which is shared by both subcells. The optimization of this contact turns out to be a major design criterion for IBC 3Ttandems. We demonstrate that our current proof of concept cells are limited by this series resistance as well as by optical losses, andwe discuss pathways to approach the simulated efficiency potential by an optimized device desig

Multi Lingual Sequent Calculus and Coherent Spaces

We study a Gentzen style sequent calculus where the formulas on the left and right of the turnstile need not necessarily come from the same logical system. Such a sequent can be seen as a consequence between different domains of reasoning. We discuss the ingredients needed to set up the logic generalized in this fashion

Stably Compact Spaces and Closed Relations

Stably compact spaces are a natural generalization of compact Hausdorff spaces in the T 0 setting. They have been studied intensively by a number of researchers and from a variety of standpoints. In this paper we let the morphisms between stably compact spaces be certain \closed relations" and study the resulting categorical properties. Apart from extending ordinary continuous maps, these morphisms have a number of pleasing properties, the most prominent, perhaps, being that they correspond to preframe homomorphisms on the localic side. We exploit this Stone-type duality to establish that the category of stably compact spaces and closed relations has bilimits

Room Temperature Atomic Layer Deposited Al2O3 Improves the Efficiency of Perovskite Solar Cells over Time

Electrical characterisation of perovskite solar cells consisting of room amp; 8208;temperature atomic amp; 8208;layer amp; 8208;deposited aluminium oxide RT amp; 8208;ALD amp; 8208;Al2O3 film on top of a methyl ammonium lead triiodide CH3NH3PbI3 absorber showed excellent stability of the power conversion efficiency PCE over a long time. Under the same environmental conditions for 355 amp; 8197;d , the average PCE of solar cells without the ALD layer decreased from 13.6 to 9.6 amp; 8201; , whereas that of solar cells containing 9 ALD cycles of depositing RT amp; 8208;ALD amp; 8208;Al2O3 on top of CH3NH3PbI3 increased from 9.4 to 10.8 amp; 8201; . Spectromicroscopic investigations of the ALD perovskite interface revealed that the maximum PCE with the ALD layer is obtained when the so amp; 8208;called perovskite cleaning process induced by ALD precursors is complete. The PCE enhancement over time is probably related to a self amp; 8208;healing process induced by the RT amp; 8208;ALD amp; 8208;Al2O3 film. This work may provide a new direction for further improving the long amp; 8208;term stability and performance of perovskite solar cell

Improved Quantum Efficiency by Advanced Light Management in Nanotextured Solution Processed Perovskite Solar Cells

Light management strategies can increase the efficiency of perovskite single junction and tandem solar cells. In this study, we present perovskite solar cells deposited on different nanotextures by spin coating. A morphological and optoelectronic analysis demonstrates a high quality of the perovskite absorber, regardless of the substrate. Using both, a nanotexture and a sodium fluoride antireflective coating, enables us to improve the power conversion efficiency by 1.0 abs to 19.7 , when compared to its planar reference. A characterisation of the optical performance of nanotextured perovskite solar cells and rigorous optical simulations reveal that the gain in efficiency can be largely attributed to reduced reflection losses and therefore increased absorption in the perovskite. Our nanotextured perovskite solar cells reach 93.6 of the attainable current density, marking the highest reported value for perovskite single junctions and approaching those of established photovoltaic technologies. Our results demonstrate that nanotextures can be applied to solution processed perovskite solar cells and pave the way to increased power conversion efficiencies by light management not only in perovskite single junction but also perovskite silicon tandem solar cell