Silicon Doped Intermediate Band Solar Cell as a Solution for Upgrading the Efficiency of Solar Cell

Abstract

The development of intermediate band solar cell is aimed in enhancing photocurrent and preserve the output voltage due to the surge of sensitivity to solar spectrum. Sensitivity to solar spectrum increased due to two-step absorption that allows to absorption of photons having energy less than band gap energy. In this work device fabrication process and analysis of the recorded data for the doping five layer of InAs QDs in GaAs p-i-n solar cell structures is presented by aiming to enhance light absorption capability, to improve charge carrier transport and a highly efficient solar cell by growing the thin film using molecular beam epitaxy (MBE). Intermediate band solar cells (IBSCs) increase solar power conversation efficiency exceeding Shockley-Queisser, which is the maximum efficiency attainable by conventional single-junction solar cells. This can happen utilizing an intermediate band (IB) within the bandgap of the semiconductor material, allowing for the absorption of two sub-bandgap photons (with energies less than the bandgap) to excite an electron to the conduction band. And this cause for an increase of current density, and provide non-reduced output voltage, consequently efficiency of the solar cell increase. Intermediate band within the band gap of a semiconductor with Si- doping, the current density JSC decreases from 31.84 mAcm-2 for the doping level 1011cm-2 and significant increase with optimized Si-doping for the doping level 5x1011 cm-2 to 32.75 mAcm-2. Si dopants can substitute both Ga and As sites forming point defect and this attributed for the change of values of JSC and VOC, This change because of photons with energies lower than the conventional bandgap can still generate charge carriers. In general, intermediate band improve charge carriers transport by providing a path way and generating more charge carriers; doping quantum dots, or introducing impurities, can significantly improve solar energy conversion efficiency. Doping of SC modify the electronic properties of quantum dots, enhance charge separation, suppress recombination losses, and improve charge transport, ultimately leading to higher power output.