High-Efficiency Silicon/Organic Heterojunction Solar Cells with Improved Junction Quality and Interface Passivation

Area of Science:

• Materials Science
• Renewable Energy
• Semiconductor Physics

Background:

• Silicon/organic heterojunction solar cells (HSCs) offer potential for high efficiency and low cost.
• Current HSC efficiencies are limited by inferior junction quality between silicon and organic layers.
• Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and n-type silicon (n-Si) are key materials in these devices.

Purpose of the Study:

• To improve the junction quality in n-Si/PEDOT:PSS HSCs.
• To enhance the open-circuit voltage and fill factor of these solar cells.
• To achieve higher power conversion efficiencies through interface engineering.

Main Methods:

• Pretreatment of n-Si wafers using tetramethylammonium hydroxide (TMAH) solution.
• Application of a capping copper iodide (CuI) layer on the PEDOT:PSS layer.
• Fabrication of planar n-Si/PEDOT:PSS HSCs and detailed photoelectric characterization.

Main Results:

• TMAH pretreatment suppressed surface recombination and increased interfacial oxide layer thickness.
• The CuI capping layer induced a strong inversion layer, providing excellent field-effect passivation.
• Achieved a competitive open-circuit voltage of 0.656 V and a high fill factor of 78.1%.
• Attained a stable power conversion efficiency exceeding 14.3% for the planar HSCs.

Conclusions:

• Facile interface treatments significantly enhance the performance of n-Si/PEDOT:PSS HSCs.
• Combined chemical and electrical passivation strategies are effective for improving solar cell efficiency.
• The findings suggest pathways for further optimization of silicon/organic solar cells to unlock their full potential.