Modeling and Simulation of Device Performance in Organic Photovoltaics

Abstract

We present a pipeline to study the device performance of organic solar cells in silico. We introduce a mathematical model that includes the dynamics of excitons as well as their dissociation at bulk heterojunctions within the nanomorphology of the active layer. This is combined with realistic morphologies that we obtain from a detailed phase field model. To solve the coupled nonlinear system, we use a finite element discretization, robust linear solvers, and three numerical schemes, Newton, Gummel, and Semi--Newton--Gummel. This allows for an efficient simulation of the complete OPV device and results in current-voltage curves that can readily be compared to measured data.

Figures (16)

• Figure 1: Sketch of an organic solar cell containing an organic active layer, top, and bottom electrode. The active layer consists of self-assembled pure donor (polymer) and acceptor (NFA) regions, indicated by the blue and red areas.
• Figure 1: Morphology (left) and snapshots of the electron density (middle) and hole density (right) at time $t = 0.001$ in 2D, computed using the Newton method.
• Figure 2: Total currents flowing out of the boundary $\Gamma_{\mathrm{bot/org}}$: semilogarithmic plot (left) and Cartesian plot (right), computed using 2D morphologies with different blend ratios $50{:}50$, $55{:}45$, $60{:}40$, $70{:}30$, and $80{:}20$ and the Newton method.
• Figure 3: Morphology (left) and snapshots of the electron density (middle) and hole density (right) under forward bias voltages of $0.0,\mathrm{V}$ (top) and $10.0,\mathrm{V}$ (bottom) in 2D, computed using the Gummel method.
• Figure 4: Total currents flowing out of the boundary $\Gamma_{\mathrm{bot/org}}$: semilogarithmic plot (left) and Cartesian plot (right), computed using 2D morphologies with different blend ratios $50{:}50$, $55{:}45$, $60{:}40$, $70{:}30$, and $80{:}20$ with the Gummel method.

Theorems & Definitions (1)

• Remark 2.1