Performance Comparison for Different Material Quantum Dot Single Intermediate Band Solar Cells

Abstract

Short circuit current density (Jsc) and photoelectric conversion efficiency (η) of the different material quantum dot intermediate band solar cells (QD-IBSCs) under full concentrated sunlight were compared in this work. The QD-IBSCs were designed with QDs formed from different excitonic Bohr radius semiconductors embedding in the different wide band gap materials. Modulation doping was used to realize partially filling the IB with electrons in QD, the influence of localized states from doping on IB was also considered. The performance of these SCs was numerically simulated based on the detailed balance principle. TheJscandηin QD-IBSCs can be adjusted via tuning the position and density of states of IB due to varying the mean size (d) and doping level of QDs in absorption region. Under the same doping level in an identical host gap material withΔEG=2.0 eV, theJscandηof the Si QD-IBSCs can be optimized with 4.3 nm-QDs, however, those of CdTe devices raises while those of Ge cells drops with increasing the sizes of QD from 2 nm to 8 nm. With changing the host gapΔEG, variation of the IB energy levelEHwith respect to valence band corresponding to the maximumηmwas explored, dependence ofηon the operation voltage was analyzed, and the impurity effect on theηwas taken into account. Present work indicates that an appropriate band gap material should be adopted to fabricate QDs to embed in suitable doped host gap one to obtain the high performance QD-IBSC.