III–V Multijunction Solar Cell Integration with Silicon: Present Status, Challenges and Future Outlook

Abstract

AbstractAchieving high-efficiency solar cells and at the same time driving down the cell cost has been among the key objectives for photovoltaic researchers to attain a lower levelized cost of energy (LCOE). While the performance of silicon (Si) based solar cells have almost saturated at an efficiency of ~25%, III–V compound semiconductor based solar cells have steadily shown performance improvement at ~1% (absolute) increase per year, with a recent record efficiency of 44.7%. Integration of such high-efficiency III–V multijunction solar cells on significantly cheaper and large area Si substrate has recently attracted immense interest to address the future LCOE roadmaps by unifying the high-efficiency merits of III–V materials with low-cost and abundance of Si. This review article will discuss the current progress in the development of III–V multijunction solar cell integration onto Si substrate. The current state-of-the-art for III–V-on-Si solar cells along with their theoretical performance projections is presented. Next, the key design criteria and the technical challenges associated with the integration of III–V multijunction solar cells on Si are reviewed. Different technological routes for integrating III–V solar cells on Si substrate through heteroepitaxial integration and via mechanical stacking approach are presented. The key merits and technical challenges for all of the till-date available technologies are summarized. Finally, the prospects, opportunities and future outlook toward further advancing the performance of III–V-on-Si multijunction solar cells are discussed. With the plummeting price of Si solar cells accompanied with the tremendous headroom available for improving the III–V solar cell efficiencies, the future prospects for successful integration of III–V solar cell technology onto Si substrate look very promising to unlock an era of next generation of high-efficiency and low-cost photovoltaics.