Monolithic perovskite/silicon tandem solar cells show great promise for further efficiency enhancement for current silicon photovoltaic technology. In general, an interface (tunnelling or recombination) layer is usually required for electrical contact between the top and the bottom cells, which incurs higher fabrication costs and parasitic absorption. Most of the monolithic perovskite/Si tandem cells demonstrated use a hetero-junction silicon (Si) solar cell as the bottom cell, on small areas only. This work is the first to successfully integrate a low temperature processed (≤150 °C) planar CH₃NH₃PbI₃ perovskite solar cell on a homo-junction silicon solar cell to achieve a monolithic tandem without the use of an additional interface layer on large areas (4 and 16 cm²). Solution processed SnO₂ has been effective in providing dual functions in the monolithic tandem, serving as an ETL for the perovskite cell and as a recombination contact with the n-type silicon homo-junction solar cell that has a boron doped p-type (p++) front emitter. The SnO₂/p++ Si interface is characterised in this work and the dominant transport mechanism is simulated using Sentaurus technology computer-aided design (TCAD) modelling. The champion device on 4 cm² achieves a power conversion efficiency (PCE) of 21.0% under reverse-scanning with a V_OC of 1.68 V, a J_SC of 16.1 mA cm⁻² and a high FF of 78% yielding a steady-state efficiency of 20.5%. As our monolithic tandem device does not rely on the SnO₂ for lateral conduction, which is managed by the p++ emitter, up scaling to large areas becomes relatively straightforward. On a large area of 16 cm², a reverse scan PCE of 17.6% and a steady-state PCE of 17.1% are achieved. To our knowledge, these are the most efficient perovskite/homo-junction-silicon tandem solar cells that are larger than 1 cm². Most importantly, our results demonstrate for the first time that monolithic perovskite/silicon tandem solar cells can be achieved with excellent performance without the need for an additional interface layer. This work is relevant to the commercialisation of efficient large-area perovskite/homo-junction silicon tandem solar cells.

Mixed organic-inorganic halide perovskites have emerged as a promising new class of semiconductors for photovoltaics with excellent light harvesting properties. Thorough understanding of the optical properties of these materials is important for photovoltaic device optimization and the insight this provides for the knowledge of energy band structures. Here we present an investigation of the sub-room temperature dependent optical properties of polycrystalline thin films of CH₃NH₃PbI₃ perovskites that are of increasing interest for photovoltaics. The complex dielectric function of CH₃NH₃PbI₃ in the energy range of 0.5–4.1 eV is determined between 77 K and 297 K using spectroscopic ellipsometry. An increase in optical permittivity as the temperature decreases is illustrated for CH₃NH₃PbI₃. Optical transitions and critical points were analyzed using the energy dependent second derivative of these dielectric functions as a function of temperature.

Silver has unique optical properties for topical applications such as plasmonics. The two most widely used silver optical data sets are the Palik handbook compilation and that determined by Johnson and Christy. Unfortunately these are inconsistent making realistic modelling of the likely performance of silver in optical applications difficult, with modelling producing either highly optimistic or very pessimistic results, depending on application. By critical examination and duplication of the original experiments leading to the widely accepted literature values, we show that both data sets have drawbacks and conclude that there is a need for an improved data set for realistic simulation of experimentally obtainable properties.

Textured glass is a possible means for reflection reduction of a photovoltaic module. Texturing not only increases the energy yield of the system through reduced reflection losses, but also can play a role in dissipating waste heat through enhancing convective and radiative heat loss. In this work, we describe three textured glass surfaces analytically and model them numerically at optical (400–1050 nm) and mid-infrared (MIR, 5–30 μm) wavelengths. Spectral and directional results are processed with a series of weight functions to evaluate the total transmission to determine the optical performance and the total MIR hemispherical emissivity for the thermal performance. It is found that the proposed textured surfaces could improve the total optical transmission by 3.3%–4.6% relative to planar glass for direct solar radiance and 4.9%–6.7% for diffuse component, whereas the total MIR hemispherical emissivity is boosted by 6.6%–9.3% relative. The current most commercially favored inverted pyramid pattern may not be the most effective glass surface texturing scheme based on optical and radiative enhancement or self-cleaning properties.

The economic value of a photovoltaic installation depends upon both its lifespan and power conversion efficiency. Progress toward the latter includes mechanisms to circumvent the Shockley‐Queisser limit, such as tandem designs and multiple exciton generation (MEG). Here we explain how both silicon tandem and MEG‐enhanced silicon cell architectures result in lower cell operating temperatures, increasing the device lifetime compared to standard c‐Si cells. Also demonstrated are further advantages from MEG enhanced silicon cells: (i) the device architecture can completely circumvent the need for current‐matching; and (ii) upon degradation, tetracene, a candidate singlet fission (a form of MEG) material, is transparent to the solar spectrum. The combination of (i) and (ii) mean that the primary silicon device will continue to operate with reasonable efficiency even if the singlet fission layer degrades. The lifespan advantages of singlet fission enhanced silicon cells, from a module perspective, are compared favorably alongside the highly regarded perovskite/silicon tandem and conventional c‐Si modules.