Enhancing the efficiency of perovskite solar cells: Dual serrated structure leaves no escape for sunlight

Solar energy, as a virtually inexhaustible clean power source, has been a major focus for achieving high-efficiency utilization. Recent advancements in all-perovskite tandem solar cells have demonstrated conversion efficiencies exceeding 30%. However, significant optical losses, particularly reflection-induced energy dissipation, hinder these cells from approaching their theoretical efficiency limit of 45%. Among these losses, energy dissipation due to reflection is particularly severe. A research team led by Chao Chen at the School of Optical and Electronic Information, Huazhong University of Science and Technology, China, recently proposed an innovative design a dual serrated structure in Frontiers of Optoelectronics. This design successfully reduces reflection losses by 18.34%, offering a novel pathway to overcome the efficiency bottleneck.

I. Why Does Sunlight Escape from the Cell? Reflection Loss as the Primary Obstacle

All-perovskite tandem solar cells are composed of wide-bandgap (WBG) and narrow-bandgap (NBG) perovskite layers, which theoretically enable the absorption of a broader spectrum of light. However, up to 10.84% of photons in the 300 nm-1050 nm absorption range are reflected before absorption. Notably, distinct reflection peaks exceeding 20% are observed at wavelengths of 350 nm and 950 nm, posing a significant challenge to efficiency improvement.

II. Structural Design: The Dual Serrated Structure Creates a "Photon Maze"

The research team designed periodic serrated structures at both the front and back interfaces of the cell. The front serrated structure (550 nm in height): Functions like a micro-lens array to focus more light into the WBG layer. Back serrated structure (400 nm in height): Triggers surface plasmon resonance in the infrared region, trapping photons within the NBG layer through repeated internal reflections. The combined effect of these dual structures significantly extends the optical path within the cell, forming a light trap that makes it easy for photons to enter but difficult for them to exit. Experimental results demonstrated that the current loss due to reflection decreased from 4.47 mA cm^-2 to 3.65 mA cm^-2 (an 18.34% reduction).

III. Technological Breakthroughs Behind the Leap in Efficiency

This design introduces three key innovations compared to conventional approaches. First, the dual serrated structure coordinated control mechanism overcomes the limitations of single-structure optimization by simultaneously resolving reflection challenges at both short and long wavelengths. Second, the high process compatibility of nanoimprint technology ensures seamless integration with existing industrial production lines. Third, the near-zero cost increment is achieved through geometric design optimization alone, eliminating reliance on expensive materials. Simulations demonstrate that these advancements could elevate tandem solar cell efficiency from the current 30.1% to 31.13%, marking a critical stride toward unlocking the full potential of perovskite-based photovoltaics.

IV. Turning Every Ray of Sunlight into Value

Future high-efficiency solar panels could lower electricity costs for households and businesses while ensuring stable power generation even under cloudy or low-light conditions, thereby contributing to carbon neutrality goals. The research team remains committed to developing high-efficiency, stable perovskite solar cells for practical applications. As Chao Chen, the corresponding author of the paper, stated, “We are not just designing a solar cell, we are designing the journey of sunlight—ensuring every photon finds its way home.” This insight from Wuhan’s Optics Valley may well illuminate the future of global green energy.