Understanding the Role of Charge Mobility and Recombination in Organic Photovoltaics

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Current organic photovoltaics based on bulk heterojunctions have an active absorbing layer that is typically only 70 to 100 nm thick. While this results in efficient extraction of photogenerated charge carriers, the active layer is too thin for efficient absorption of light. If the active layer were 300 nm thick, close to 100% of the light would be absorbed. However, when devices are made with thicker active layers, recombination of charge carriers reduces the overall efficiency of the device.

In this project, I conduct an in-depth analysis of the effect of charge mobility and recombination in organic photovoltaics. Using a combination of experiments and a 1D simulation software, Seftos, I explain why bulk heterojunction organic photovoltaics suffer from poor performance when made with thick active layers. I experimentally demonstrate charge mobility’s effect on reducing solar cells, then utilize it to extract values of the recombination rate constant for two organic photovoltaic systems. These results provide an overview on the role of charge mobility and recombination in device performance and a road map for designing the next iteration of bulk heterojunction systems.


Type of resource text
Date created May 26, 2015


Author Lam, David
Degree granting institution Stanford University, Department of Physics
Primary advisor McGehee, Michael D.
Advisor Burchat, Patricia R.


Subject solar cells
Subject photovoltaics
Subject organic solar cells
Subject bulk heterojunctions
Subject simulation
Subject recombination
Subject charge mobility
Genre Thesis

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This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).

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Preferred Citation
Lam, David (2015). Understanding the Role of Charge Mobility and Recombination in Organic Photovoltaics. Stanford Digital Repository. Available at: http://purl.stanford.edu/jz758vk2584


Undergraduate Theses, Department of Physics

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