World-record solar efficiency: China pushes boundaries of renewable energy

A groundbreaking achievement in solar technology is setting new standards for renewable energy efficiency. Chinese researchers have unveiled a tandem solar cell that combines cutting-edge perovskite and copper-indium-gallium-selenide (CIGS) materials.

Eco News reveals in a fresh article that Chinese researchers have successfully created four-terminal (4T) perovskite-CIGS tandem solar cells that boast a world-record efficiency of 29.36 per cent. This achievement sets a new standard in solar energy conversion and highlights the remarkable progress of perovskite, a material that once had limited efficiency, but now shows immense potential.

Perovskite, discovered in the 19th century, has long intrigued scientists due to its unique crystal structure. However, in the early days of photovoltaic research, perovskite solar cells were hindered by poor efficiency and even worse stability, preventing them from being viable for commercial use. 

Regarded by many as an “impossible material” because it easily degraded under environmental conditions like heat and moisture, perovskite presented significant challenges. Despite these hurdles, researchers have continued to explore ways to enhance its stability and efficiency.

Recent advancements in material engineering have turned perovskite into one of the most promising materials for solar cells. Perovskite-silicon tandem cells now achieve efficiencies of 40 per cent, and standalone perovskite cells continue to break new records. The remarkable performance of the 4T perovskite-CIGS tandem solar cell demonstrates that perovskite has evolved from a theoretical material to a leading force in the future of renewable energy.

Researchers at Northwest Normal University have developed a new tandem solar cell combining a perovskite-based top layer with a copper-indium-gallium-selenide (CIGS) bottom layer. This hybrid structure allows the cell to capture a broader spectrum of sunlight, boosting its overall efficiency. The perovskite layer is semi-translucent, permitting some light to pass through to the CIGS bottom layer.

This multi-layer design enables the tandem cell to efficiently utilize various wavelengths of sunlight. The perovskite top cell absorbs high-energy photons, while the CIGS bottom layer captures low-energy photons, optimizing the energy conversion process.

To enhance the quality of the perovskite layer, the researchers used a solvent-annealing technique with dimethyl sulfoxide (DMSO) and applied heat in two stages, first at 100°C and then at 80°C, promoting crystal growth.

As a result, they achieved a perovskite film with high purity, improved crystallinity, and larger grain sizes, free of detectable lead iodide contamination. This upgraded semiconductor allowed the perovskite top cell to reach an efficiency of 21.26 per cent with a bifaciality factor of 92.2 per cent. Coupled with the CIGS bottom cell, the tandem structure achieved a total efficiency of 29.36 per cent, setting a new record for 4T perovskite-CIGS solar cells.

By Naila Huseynova