Magnesium-doped quantum dots boost perovskite/organic tandem solar cell stability

Photovoltaic (PV) options, that are designed to transform daylight into electrical power, have gotten more and more widespread worldwide. Over the previous many years, engineers specialised in power options have been attempting to establish new photo voltaic cell designs and PV supplies that would obtain even higher energy conversion efficiencies, whereas additionally retaining their stability and reliably working for lengthy intervals of time.

The numerous rising PV options which have confirmed to be notably promising embrace tandem solar cells primarily based on each perovskites (a category of supplies with a attribute crystal construction) and natural supplies. Perovskite/natural tandem photo voltaic cells could possibly be extra inexpensive than present silicon-based photo voltaic cells, whereas additionally yielding greater energy conversion efficiencies.

These photo voltaic cells are manufactured utilizing wide-bandgap perovskites, which have an digital bandgap larger than 1.6 electronvolts (eV) and might thus take in higher-energy photons. Regardless of their enhanced capability to soak up high-energy gentle particles, these supplies have important limitations, which usually adversely influence the soundness of photo voltaic cells.

Researchers on the Hong Kong Polytechnic College lately devised a brand new technique to enhance the soundness and effectivity of perovskite/natural tandem photo voltaic cells. This technique, outlined in a paper in Nature Vitalitydepends on using acidic magnesium-doped tin oxide quantum dots.

“Wide-bandgap perovskites in monolithic perovskite/organic tandem solar cells face challenges such as unregulated crystallization, severe defect traps, poor energetic alignment and undesirable phase transitions, primarily due to unfavorable bottom interfacial contact,” wrote Yu Han, JieHao Fu, and their colleagues of their paper.

“These issues lead to energy loss and device degradation. In this article, we synthesize acidic magnesium-doped tin oxide quantum dots to modulate the bottom interface contact in wide-bandgap CsPbI₂Br perovskite solar cells.”

Quantum dots are nanoscale semiconductor particles that exhibit distinctive optical and digital properties. The researchers synthesized quantum dots doped with acidic magnesium after which used them to reinforce the connection between the perovskite layer and underlying materials in perovskite/organic solar cells.

“This design balances physical, chemical, structural and energetic properties, passivating defects, optimizing energy band alignment, enhancing perovskite film growth and mitigating instability,” wrote the researchers. “We also elucidate the instability mechanism caused by alkaline-based tin oxide bottom contact, emphasizing the impact of the tin oxide solution’s acid/base properties on the stability and performance of the device.”

The researchers used their new quantum dot-based design technique to create a wide-bandgap CsPbI₂Br photo voltaic cell after which examined the efficiency of this cell in a collection of exams. Their outcomes had been promising, as their method yielded good energy conversion efficiencies, whereas additionally boosting the photo voltaic cell’s stability underneath quite a lot of environmental situations.

“The wide-bandgap CsPbI₂Br solar cell achieves a power conversion efficiency of 19.2% with a 1.44 V open-circuit voltage,” wrote the researchers. “The perovskite/organic tandem solar cell demonstrates an efficiency of 25.9% (certified at 25.1%), with improved stability under various conditions.”

The latest work by Han, Fu and their collaborators may contribute to the development of perovskite/natural tandem photo voltaic cells, doubtlessly facilitating their future widespread deployment. The quantum dot-based technique they developed may quickly be improved additional and utilized to comparable photo voltaic cells primarily based on different supplies.

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