Suppressing Electrode Diffusion With a PMMA Metal-Capture Mesh Enables Stable Conventional Organic Photovoltaics

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Conventional organic photovoltaics (OPVs) face premature failure due to top-electrode metal diffusion into organic layers under thermal stress.
• Silver (Ag) diffusion is identified as a critical failure pathway in high-efficiency OPVs, leading to interfacial traps and leakage.

Purpose of the Study:

• To suppress Ag diffusion in OPVs without compromising charge extraction.
• To enhance the operational stability and longevity of high-efficiency conventional OPVs.

Main Methods:

• Introduction of polymethyl methacrylate (PMMA) to self-assemble into a discontinuous, mesh-like network on the PDINN layer.
• Utilizing spectroscopic analyses to investigate PMMA-Ag interactions (Ag-O coordination).
• Evaluating device performance and stability under various accelerated aging conditions (ISOS-D-1I, ISOS-D-2I, ISOS-L-3).

Main Results:

• PMMA acts as both a physical diffusion barrier and a chemical metal-capture mesh, effectively blocking Ag migration.
• PMMA-modified OPVs achieved a power conversion efficiency (PCE) of 20.2%.
• Enhanced stability demonstrated by retaining >80% PCE after 3,574 hours of shelf storage and significantly improved thermal aging resistance (T80 of 105 hours vs. 10 hours for controls).

Conclusions:

• PMMA effectively mitigates electrode-diffusion-induced failure in high-efficiency conventional OPVs.
• The strategy of using PMMA as an interfacial layer is broadly applicable to other electrode metals (Cu, Au) and OPV architectures.
• This approach offers a viable solution for improving the long-term stability and commercial viability of organic solar cells.