Tandem Solar Cell Technologies and Optimization

Tandem solar cells combine two or more sub-cells with different bandgaps to harvest a broader portion of the solar spectrum and surpass the Shockley–Queisser limit of single-junction devices. Architectures range from monolithic two-terminal integration—where sub-cells are series-connected via interlayers—to mechanically stacked four-terminal configurations that allow independent operation of each sub-cell. Metal-halide perovskites have emerged as versatile top-cell materials, pairing effectively with silicon, CIGS or other perovskites in both laboratory and pilot-scale devices. Key optimisation strategies encompass optical management through nanotexturing and anti-reflection schemes, spectral splitting or semi-transparent electrodes, precise control of absorber thickness for current matching, carrier-selective contact engineering, defect passivation and bandgap tuning via compositional engineering. These advances have driven certified efficiencies towards or beyond 30 %, while improvements in yield, stability and manufacturability underpin the global role of tandem photovoltaics in reducing levelised cost of electricity and accelerating decarbonisation.

Research from Nature Portfolio

Periodic nanotextures in perovskite–silicon tandems have been shown to reduce reflection losses, boost fabrication yield from 50 % to 95 % and enhance open-circuit voltage by 15 mV, leading to a certified 29.8 % power conversion efficiency in monolithic devices. An alternative approach increased the optical path length in perovskite films via boosted solvent extraction and Lewis-base passivation, extending electron-diffusion length to 2.3 µm; semi-transparent top cells reached 19 % efficiency and tandems with silicon achieved 28.2 % PCE. Foundational work introduced a low-temperature processed semi-transparent perovskite cell using hydrogenated indium oxide rear electrodes, delivering 14.2 % efficiency, 72 % near-infrared transmittance and four-terminal tandem operation at 20.5 % efficiency, thereby establishing key design principles.

Tandem Solar Cell Technologies and Optimization publication trend

The graph below shows the total number of articles in tandem solar cell technologies and optimization across all publications each year (not limited to Nature Index journals).

Technical terms

Tandem solar cell: Photovoltaic device stacking sub-cells of different bandgaps to expand spectral utilisation and exceed single-junction limits.

Monolithic two-terminal: Integrated tandem architecture with sub-cells series-connected through an interlayer for single-output operation.

Four-terminal configuration: Mechanically stacked sub-cells with independent electrical connections, enabling optimal bias for each junction.

Power conversion efficiency (PCE): Ratio of electrical power output to incident solar power, expressed as a percentage.

Current matching: Optimisation of sub-cell photocurrents in series-connected tandems to avoid performance bottlenecks.

Fill factor (FF): Metric of the “squareness” of a solar cell’s current–voltage curve, indicating the quality of charge extraction.

Bandgap: Energy difference between valence and conduction bands that determines the photon absorption threshold of a material.

Passivation: Chemical or physical treatment that neutralises electronic defects, reducing recombination and improving voltage.

Optical management: Strategies such as texturing, anti-reflection coatings and spectral splitting to maximise light absorption and minimise losses.

References

1. Conductive passivating contact for high fill factor monolithic perovskite/silicon tandem solar cells. Interdisciplinary Materials (2023).
2. Low-temperature-processed efficient semi-transparent planar perovskite solar cells for bifacial and tandem applications. Nature Communications (2015).
3. Enhanced optical path and electron diffusion length enable high-efficiency perovskite tandems. Nature Communications (2020).
4. Nano-optical designs for high-efficiency monolithic perovskite–silicon tandem solar cells. Nature Nanotechnology (2022).
5. Perovskite/CIGS Tandem Solar Cells: From Certified 24.2% toward 30% and Beyond. ACS Energy Letters (2022).
6. Ligand-bridged charge extraction and enhanced quantum efficiency enable efficient n–i–p perovskite/silicon tandem solar cells. Energy & Environmental Science (2021).