Optimization of Third Generation Nanostructured Silicon- Based Solar Cells

Abstract

Recently, the demand of solar cells has rapidly been growing with an increasing social inter‐ est in photovoltaic energy. Improving the energy conversion efficiency of solar cells by de‐ veloping the technology and concepts must be increasingly extended as one of the key components in our future global energy supplement, but, the main problem of photovoltaic modules are their rather high production and energy cost. Third generation solar cell is an alternative type of the promising device, which aims to ach‐ ieve high-efficiency devices with low cost in comparison with expensive first generation so‐ lar cells and low-efficiency second generation solar cells. One of the prominent types is Sibased third generation solar cells which benefit from thin film processes and abundant, nontoxic materials. To gain efficiencies more than Shockley and Queisser limit which states the theoretical upper limit of 30% for a standard solar cell and overcome the loss mecha‐ nisms in this generation, different methods have been proposed: 1. Utilization of materials or cell structures incorporating several band gaps: • Si-based multi-junction solar cells 2. Modification of the photonic energy distribution prior to absorption in a solar cell: • Photon energy down-conversion • Photon energy up-conversion 3. Reducing losses due to thermalization: • Hot carrier solar cells • Impact ionization solar cells