Prospects of light management in perovskite/silicon tandem solar cells

Abstract

Perovskite/silicon tandem solar cells are regarded as a promising candidate to surpass current efficiency limits in terrestrial photovoltaics. Tandem solar cell efficiencies meanwhile reach more than 29%. However, present high-end perovskite/silicon tandem solar cells still suffer from optical losses. We review recent numerical and experimental perovskite/silicon tandem solar cell studies and analyse the applied measures for light management. Literature indicates that highest experimental efficiencies are obtained using fully planar perovskite top cells, being in contradiction to the outcome of optical simulations calling for textured interfaces. The reason is that the preferred perovskite top cell solution-processing is often incompatible with usual micropyramidal textures of silicon bottom cells. Based on the literature survey, we propose a certain gentle nanotexture as an example to reduce optical losses in perovskite/silicon tandem solar cells. Optical simulations using the finite-element method reveal that an intermediate texture between top and bottom cell does not yield an optical benefit when compared with optimized planar designs. A double-side textured top-cell design is found to be necessary to reduce reflectance losses by the current density equivalent of 1 mA/cm2. The presented results illustrate a way to push perovskite/silicon tandem solar cell efficiencies beyond 30% by improved light management.

Nano-optical designs enhance monolithic perovskite/silicon tandem solar cells toward 29.8% efficiency

“…In view of process robustness we performed a numerical sensitivity analysis to study the influence of layer thicknesses in the top cell on the photogenerated current density. We used data sets obtained during a Bayesian optimization based on the finite element method (FEM) similar to previous work 14 . Figure 3d shows a cross section through a meshed unit cell of a PSTSC with nanotextures between perovskite and silicon subcells, as is used in the FEM simulations.…”

“…The data for sensitivity study presented in Fig. 3 was generated during a layer-thickness optimization with a Bayesian optimization algorithm 45 , similar to an optimization we presented in previous work 14 .…”

“…In addition, various publications addressed the improvement of the electronic properties by optimizing contact layers 1 , utilizing additives [8][9][10] and adjusting the perovskite composition 11 or deposition 12 . Numerical studies predict a further increase of PCE with adequate light management by introducing textured device interfaces 13,14 . For silicon solar cells, potassiumhydroxide etched random pyramidal textures with a size of several micrometers are commonly used for light management.…”

Emerging Perovskite Solar Cell Technology: Remedial Actions for the Foremost Challenges

“…[ 77 ] The monolithic perovskite–silicon tandem solar cell engineered with sinusoidal nano texures, play a crucial role in the light management of the PV devices. [ 78 ]…”

Detailed-balance efficiency limits of two-terminal perovskite/silicon tandem solar cells with planar and Lambertian spectral splitters

“…incoupling and backreflection from the bottom cell are also relevant; they are not discussed here. 20 Spectral splitting can be achieved by an additional interlayer between the top and bottom cells that effectively reflects the part of the spectrum with energy above the bandgap of the top cell, and that transmits the remainder to the bottom cell. In an ideal case, the low-and highenergy spectral bands are fully split between the cells, so maximum current and voltage can be harvested.…”