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Abstract:

Perovskite/silicon tandems have smashed through the 30% efficiency barrier, which represents a promising step towards high efficiency solar modules. However, the processing used to fabricate high efficiency devices is not compatible with mass production. For this technology to be impactful in the urgent fight against climate change and be scalable to the multi-terawatt (TW) level, a shift in mindset is required when designing the silicon bottom cell. In this work, we outline the design requirements for the silicon cell, with a particular focus on the constraints imposed by industrial processing. In doing so, we discuss the type of silicon wafers used, the surface treatment, the most appropriate silicon cell architecture and the formation of metal contacts. Additionally, we frame this discussion in the context of multi-TW markets, which impose additional constraints on the processing relating to the sustainability of the materials used. The discussion herein will help to shape the design of future silicon solar cells for use in tandems, so that the LCOE of solar electricity can be driven to new lows.

Abstract:

Computations of the molecular parameters and relative populations are reported for the two isomers of Er 3 N@C 80 experimentally known, i.e. produced by encapsulation into the isolated-pentagon-rule (IPR) C 80 cages with I h and D 5 h symmetries. The calculations are mostly based on the density-functional theory (DFT) treatments with the B3LYP functional. However, the inter-isomeric energetics is further refined with the B2PLYP method which places the D 5 h endohedral higher in the potential energy by 18.8 kcal/mol. The isomeric populations are evaluated using the Gibbs energy in a broad temperature interval. The computations performed with the floating-encapsulate-model (FEM) treatment agree with the observation that Er 3 N@ I h (7)-C 80 represents the major isomer. The calculations also suggest some similarity between Er 3 N@C 80 and Lu 3 N@C 80 so that Er 3 N@C 80 could possibly also produce a useful nanowire, like recently found with Lu 3 N@C 80 and its interesting electrical-conductivity and switching behavior.