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Mathematical Models for Nano Science - Politecnico di Milano

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Model equations - 1<br />

• Exciton<br />

equation<br />

⎧<br />

∂X<br />

∂t + <strong>di</strong>v J X = G − X τ X<br />

⎪⎨<br />

∂X<br />

∂t + <strong>di</strong>v J X = G − X −<br />

X + ηk rec P<br />

τ X τ <strong>di</strong>ss<br />

J X = −D X ∇X<br />

in Ω n ∪ Ω p<br />

in Ω H<br />

in Ω<br />

X = 0<br />

on Γ C ∪ Γ A<br />

⎪⎩<br />

X (x, 0) = X 0 (x) in Ω.<br />

• Excitons have null net charge → Only <strong>di</strong>ffusion (Fick law)<br />

• Generation term G(x, t): constant, Beer-Lambert<br />

• Exciton lifetime τ X , geminate pair <strong>for</strong>mation time τ <strong>di</strong>ss<br />

• Geminate pair recombination rate constant k rec and triplet<br />

exciton fraction η<br />

• X and J X are continuous in Ω

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