Efficiency enhancement in a single bandgap silicon solar cell considering hot-carrier extraction using selective energy contacts.

One of the most important and challenging loss factors of photovoltaics is the heat production of energetic carriers excited by high energy incident photons. The present work shows that if carriers are extracted at their high energies before cooling down due to scattering, the conversion efficiency can be noticeably enhanced. To increase the efficiency of a single-band gap solar cell in this work, selective energy contacts are introduced to a p-i-n structure to extract hot carriers. A selective energy contact solar cell is made up of many collecting contacts with particular energy differences from the conduction band of the cell. In other words, each contact could extract carriers with a special range of energies. The concept of selective energy contact solar cells is to collect high energy carriers, i.e. electrons in this case, within a range of energies onto external electrodes before they cool down. The comparison between conventional solar cells and selective energy contact solar cells shows a significant enhancement in electron collection and efficiency. Based on simulation results, it is observed that the efficiency of the selective energy contact solar cell has been enhanced substantially exceeding almost twice as much as a conventional solar cell's and reaching a significant 34% efficiency.