Gold nanoparticles in solar cells: A delicate balance

Organic solar cells (OSCs) are light, flexible, and inexpensive, making them an excellent alternative photovoltaic material. A downside is their inherent thinness, which limits their efficiency.

Adding gold nanoparticles into the active layer is a common method for increasing OSCs’ absorption, but it comes at a cost. The nanoparticles can also lead to degradation in OSCs if not used at the right concentration, specifically low mobility, unintentional doping, and charge carrier trapping.

To develop a clear diagnostic picture of the degradation pathways that impact OSCs, Tabish Janwari and Najeeb-ud-din Hakim simulated various imperfections in a P3HT:PCBM-based OSC with gold nanoparticles and identified how each defect affected how the device functions.

Their tests used P3HT:PCBM solar cells, a common medium for solar cell benchmarking. They found that even a small electronic instability or morphological imbalance can outweigh the optical gains the gold provides.

“The most critical failure mechanism in gold nanoparticle organic solar cells is the increase in trap-assisted recombination,” said Janwari. “Enhanced plasmonic absorption undoubtedly improves photogeneration; however, trap-induced recombination can offset these gains if not carefully managed, making trap formation and recombination the primary mechanism to monitor in long-term stability and device design.”

Solar cell manufacturers can balance the benefits of embedded nanoparticles with the risk of new degradation pathways by optimizing nanoparticle size and concentration to avoid creating deep trap states, adding dielectric coatings to the nanoparticles, and adding a barrier to limit nanoparticle migration. Janwari also suggests comprehensive testing to identify early signs of problems.

“By combining plasmonic design optimization with careful stability engineering, manufacturers can retain the optical gains of nanoparticles while suppressing the associated degradation mechanisms,” said Janwari.

Source: “Modeling and characterization of degradation mechanisms in gold nanoparticle-enhanced P3HT: PCBM organic solar cells,” by Tabish Janwari and Najeeb-ud-din Hakim, Journal of Renewable and Sustainable Energy (2025). The article can be accessed at https://doi.org/10.1063/5.0291390 .