Silicon Perovskite Tandem Solar Cell Molecular Additive To Boost Solar Cell Efficiency To 32.76%

While there is ongoing research and advancements in other solar cell technologies, such as Spin-Flip in metal complexes, that are expected to boost power conversion efficiencies past the 60% mark, silicon still remains the dominant and most practical material to use to make solar cells currently. The primary problem with silicon semiconductor solar cells is their low power conversion efficiency rate of around 20%, with monocrystalline being the market dominant standard that has the highest efficiency figures of around 22–25% and 30–40 year lifespans.

Perovskite, a high-performance semiconductor, is widely regarded as the material to replace silicon in solar cells because it offers over 30% efficiency when converting sunlight into electricity. The material also has the potential to lower solar cell production costs. However, perovskite hasn’t gone mainstream. Why? The semiconductor degrades faster than silicon because it crystallizes easily.

What Causes Perovskite To Crystallize?

When exposed to heat, moisture, or bright light, perovskite semiconductors tend to crystallize, which results in the material experiencing defects in its electricity semiconducting properties. These defects include forming voids (tiny empty spaces) and separation of chemical components, all of which make the solar cells duds.

To try to get the best of both worlds, researchers and engineers have been developing tandem solar cells, which combine silicon and perovskite placed as separate layers (one above the other) to enhance efficiency and durability. However, this hasn’t worked because:

1. The cells have not achieved the desired power conversion efficiency figures.

2. Cells degrade quickly over time.

The primary challenge here is crystallization because the silicon layer absorbs heat and warms up rapidly during tandem solar cell manufacturing, transferring this heat to the surrounding areas, including to the perovskite layer, making it crystallize and lose efficiency.

In their research paper, Qilin Zhou et al (2026) discovered that the thin silicon wafers used to make tunnel oxide passivated contact tandem solar cells feature a reduced thermal mass and higher thermal conductivity, factors that accelerate heat transfer during perovskite subcell deposition. This accelerated heat transfer causes quick crystallization of the perovskite layer, which degrades the film’s quality and compromises the tandem solar cell’s performance.

Proposed Solution To Prevent Perovskite Crystallization During Subcell Deposition

Heat transfer from the silicon layer to the perovskite layer during subcell deposition cannot be avoided. So the research team turned to control measures, where they used 2-mercaptobenzothiazole to regulate the perovskite crystallization dynamics. This chemical additive exhibits dual-mode binding with perovskite organic cations, effectively slowing down the semiconductor’s crystallization process, making it possible to yield more uniform films that have fewer defects.

In technical terms, the addition of this 2-mercaptobenzothiazole chemical enhances morphological uniformity while also eliminating voids and suppressing halide segregation. At the same time, it reduces the non-radiative recombination and lowers the trap-assisted recombination rate to 4.3 × 104 cm s−1 from 3.2 × 105 cm s−1.

As a result, the two-terminal monolithic perovskite/tunnel oxide passivated contact tandem solar cell attained a certified stabilized power conversion efficiency of 32.76%. The prototype they built retained 91% of this 32.76% conversion efficiency after 1,700 hours of continuous operation, which is slightly over 2 months (70 days). This testing period and the results indicate the proof of concept is viable for commercial applications.

Implications of this Research in Commercial Applications

This tandem solar cell manufacturing approach has exposed the previously overlooked perovskite crystallization issue on industrial silicon wafers during subcell deposition. The research team’s findings might soon be adapted by other solar cell manufacturers and applied to these sunlight-to-electricity conversion structures that use different perovskite materials.

A power conversion efficiency increase of 5–10% might seem insignificant, but it adds up. For instance, in a solar farm that has an installed capacity of 100MW, a 10% increase could see the output rise to 110MW, and this extra 10MW is enough to power around 2,500 homes.

How This Research Applies to Current Events

Considering recent global events, particularly the blockage of the Strait of Hormuz by Iran due to the ongoing conflict with the US and Israel, global oil energy markets have been thrown into turmoil because this waterway controls 20% of the world’s oil and natural gas traffic from various production sites in the Middle East. This blockade has created the largest single interruption to global oil trade in history, but the surprising thing is that it is not causing as much pain at the pump as past oil energy crises. The reason being, our modern world has a more diverse energy mix.

Solar in particular plays a more significant role on the global energy consumption map. In 2015, this energy source provided only 1% of the world’s electricity (228 GW), but this skyrocketed to 2,919 GW in a span of only 10 years, providing 9% of the world’s electricity. Solar has officially overtaken nuclear energy and is projected to provide 9,000 GW by 2030, which represents 20% of the global energy demand.

This energy source has become too cheap to fail, and advancements in the technology enabled by such research into silicon perovskite tandem solar cells will only make it cheaper and easier to adopt both at personal levels in homes and nationally via investments in large scale solar farms. Since this research focuses on increasing the power conversion efficiencies of solar cells, it means the same space currently under solar installation in solar farms, home rooftops, offices, etc., will be able to generate more power. Space is usually an issue in solar installations, so making each panel more energy dense can solve this issue.

With this increase in solar energy generation and the increasing adoption of EVs, oil crises like the one we face today might be insignificant in the future.

This research was published by a team led by Qilin Zhou and is published in the Nature Energy Journal titled “Additive-assisted perovskite crystallization on industrial TOPCon silicon for tandem solar cells with improved efficiency”.