Improving solar technology involves more than turning light to electricity efficiently. It’s also about controlling how the electrical charges inside the material behave after that light is absorbed. A new study from Canada has tackled one of the subtler challenges in this process, improving the movement of positive charges, known as “holes” — meaning the absence of an electron, that moves in the opposite direction — through the layers of a solar cell. Both electrons and holes must travel efficiently for the cell to deliver maximum power.
The Challenge: Positive Charges Get Stuck
In many modern thin-film solar cells, the part of the device that carries holes — called the hole transport layer — can slow them down or let them recombine with electrons before they reach their destination. This wastes much of the captured sunlight as heat instead of electricity.
The Canadian team worked with perovskites, which have achieved impressive efficiencies in the lab but still face real-world reliability and performance bottlenecks. Their focus was on making a better hole transport layer by fine-tuning its chemistry to reduce defects and improve the interface with the light-absorbing layer.
What’s New in This Study
By adjusting the molecular structure of the hole transport layer, the researchers created a smoother, more uniform pathway for holes to travel. This not only sped up their movement but also reduced the rate at which they were lost to recombination.
Lab tests showed a measurable increase in the overall efficiency of the solar cell, alongside better stability when exposed to light and heat; two conditions that have been known to degrade perovskite cells quickly.
Why This Matters for the Energy Transition
Perovskite solar cells are already cheaper to produce in theory than traditional silicon panels, and they can be made on flexible, lightweight substrates. But small inefficiencies at the microscopic level can add up to major energy losses in large-scale use.
By addressing the specific challenge of hole transport, this research closes one of the remaining performance gaps, bringing perovskite technology closer to being a competitive, durable option for rooftops, solar farms, and portable power systems.
Looking Ahead
The principles demonstrated here could also apply to tandem solar cells — devices that stack multiple light-absorbing layers to capture a broader range of the solar spectrum. In those systems, controlling both electron and hole transport is even more critical.
If scaled successfully, these improvements could help push solar energy costs down further, making clean power more accessible while speeding up the replacement of fossil fuels.
Source
In-situ self-assembly of hole transport monolayer during crystallization for efficient single-crystal perovskite solar cells, Nature Communications, 2025-08-6
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