Energy band structure and absorption coefficients in the quantum-dot intermediate band solar cells

This paper describes a net generation balance model to study the qasi-Fermi level split and the intermediate band (IB) filling. Our simulations reveal that the QD state density is not enough high to pin the IB quasi-Fermi level (Ef_IB) at the position of the IB level (E_IB), and the filling factor (f) is determined by the absorption-recombination process of sub-bandgap photons. In the quasi-uniform absorption (equivalent absorption coefficients), a rough approximation is that Ef_IB parallel with E_IB, and is clamped in the equilibrium position. In the nonuniform absorption case (inequivalent absorption coefficients), our simulations suggest that optimizing α_IC0/α_VI0 ratio can effectively enhance the conversion efficiency.