PROJECTS: High efficiency Quantum dot solar cells
This word is aimed to develop ultra high efficiency solar cells based on self assembled quantum dot (QD) nanostructures. We are incorporating III-(As, Sb) quantum dots into the i-region of a p-i-n junction for multi-photon absorption. Based on theoretical predictions, these QD solar cells have potential for efficiencies greater than 50%. In this device, we utilize the unique benefits of an intermediate band formed by the electron levels in quantum dots. This device can produce not only high open circuit voltages (> 1.7 eV) but also large short-circuit currents due to the absorption of sub band gap photons. In the proposed structure, the barrier material can absorb wavelengths below 700 nm while multi-photon processes in quantum dots can be used to absorb wavelengths up to 2 Ám. Our material flexibility can help tune the energy bandgap of the barrier material and quantum dot to their respective optimum values. This device is expected to outperform single or multi-junction solar cells in terms of energy conversion efficiency and cost. A key milestone towards achieving the claimed high-efficiency solar cell device is flexibly tuning the energy bandgap of the barrier material and QD according to the designed values.