Can these tandems be made without expensive, toxic processes that would lock out poorer regions?
Yes—recent breakthroughs show that perovskite-silicon tandems can be fabricated in open air using a common alcohol solvent, n-butanol (nBA), instead of toxic antisolvents or inert-gas chambers. A 2024 study demonstrated that nBA's low polarity and moderate evaporation rate actually protect the perovskite film from moisture during coating, achieving a certified 28.7% efficiency on a small cell and 26.3% on a 16 cm² module [1]. This means factories don't need expensive gloveboxes or hazardous solvent-handling systems, lowering the capital barrier for manufacturing in developing economies.
Another 2023 study used a triple-source evaporation method (PbI₂, PbCl₂, CsBr) combined with a framework-heat-treatment to create a quasi-2D structure that allows organic salt to penetrate fully, yielding 28.3% stable efficiency and retaining 94% of performance after 1,200 hours of operation [6]. This approach avoids the need for spin-coating, which is hard to scale, and instead uses blade-coating—a technique already common in roll-to-roll printing. Together, these results show that high-efficiency tandems can be made with processes that are both scalable and less dependent on specialized infrastructure.
Do these cells rely on scarce materials that could create new dependencies?
The most critical scarce material in current tandems is indium, used in transparent conductive oxide (TCO) layers. A 2023 study from Nature showed that replacing the standard crystalline TCO with an ultrathin (5 nm) amorphous indium zinc oxide (IZO) layer reduces indium consumption by approximately 80% while still enabling a certified 32.5% efficiency [5]. This is a game-changer because indium is a byproduct of zinc mining, with supply concentrated in a few countries. Cutting indium use by four-fifths dramatically reduces the risk of a new resource-based equity divide.
Other studies confirm that high efficiencies can be achieved without exotic materials. For example, a 2024 tandem using a bilayer passivation strategy (lithium fluoride + diammonium diiodide) on standard Czochralski silicon reached a certified 33.89% efficiency—the first two-junction cell to exceed the single-junction Shockley-Queisser limit of 33.7% [3]. This device used industry-standard silicon wafers and common perovskite precursors, not rare elements. Similarly, a 2023 Science paper achieved 31.25% certified efficiency using an additive to control perovskite crystallization on standard micrometric-pyramid textured silicon [4]. The consistent theme is that the highest efficiencies are being demonstrated with widely available materials, not exotic ones.
Will these cells last long enough to be equitable investments?
Early stability data is promising but still limited—most studies report hundreds to a few thousand hours of operation, not the 25+ years expected of commercial silicon panels. A 2023 study reported that encapsulated tandems retained over 80% of initial performance after 2,000 hours of continuous full-sun illumination at room temperature [2]. Another 2023 study showed 94% retention after 1,200 hours [6]. These are encouraging but far short of the multi-decade lifetimes needed for equitable deployment, where a panel that fails early would disproportionately burden low-income adopters.
Stress from thermal expansion mismatches between layers is a known challenge. A 2023 review noted that perovskite and organic layers have thermal expansion coefficients roughly ten times higher than TCO films and glass, which can induce compressive or tensile stress during temperature changes [7]. This stress can degrade performance over time. However, the same review points out that strain engineering—such as using flexible interlayers—is an active area of research. The bottom line: stability is improving rapidly, but the technology is not yet proven for the 25-year lifespans that would make it a safe investment for all income levels.
About These Sources
This answer is built on 7 peer-reviewed studies — published from 2023 to 2024, 2 from 2024 or later, 7 in Q1 journals, collectively cited 1,441 times — selected as the most relevant from 12 studies that passed quality screening, drawn from 49 papers retrieved from a database of over 500 million.
Sources used in this answer
Solvent engineering for scalable fabrication of perovskite/silicon tandem solar cells in air
Demonstrates that using n-butanol (nBA) solvent enables air fabrication of perovskite/silicon tandems, achieving 29.4% (certified 28.7%) efficiency on small cells and 26.3% on 16 cm² modules, reducing the need for inert atmospheres.
Efficient Perovskite/Silicon Tandem Solar Cells on Industrially Compatible Textured Silicon
An anion-engineered additive strategy improves perovskite film crystallinity on industrially textured silicon, yielding 28.6% (certified 27.9%) efficiency and >80% performance retention after 2,000 hours of operation.
Perovskite/silicon tandem solar cells with bilayer interface passivation
A bilayer passivation strategy (LiF + diammonium diiodide) on double-textured Czochralski silicon achieves a certified 33.89% efficiency, the first two-junction cell to exceed the single-junction Shockley-Queisser limit of 33.7%.
Interface passivation for 31.25%-efficient perovskite/silicon tandem solar cells
Using an additive to control perovskite crystallization on standard micrometric-pyramid textured silicon yields a certified 31.25% efficiency on 1.17 cm² active area.
Enhanced optoelectronic coupling for perovskite/silicon tandem solar cells
Replacing crystalline TCO with ultrathin (5 nm) amorphous indium zinc oxide (IZO) reduces indium consumption by ~80% while achieving a certified 32.5% efficiency, addressing material scarcity concerns.
Inorganic Framework Composition Engineering for Scalable Fabrication of Perovskite/Silicon Tandem Solar Cells
A triple-source coevaporation method (PbI₂, PbCl₂, CsBr) combined with framework-heat-treatment produces a quasi-2D structure, achieving 28.3% stable efficiency and 94% performance retention after 1,200 hours.
Stress and Strain in Perovskite/Silicon Tandem Solar Cells
Reviews stress/strain issues in perovskite/silicon tandems, noting that thermal expansion coefficients of perovskite and organic layers are ~10× higher than TCO and glass, which can induce stress during temperature changes.