Emergent Materials and Concepts for Solar Cell Applications

Abstract

The recent years saw a remarkable progress in solar cell materials and designs. Among all the available photovoltaic technologies, two of them stand out from the rest because of very rapid efficiency growth: III–V semiconductors and perovskite-based solar cells (PSC). In this chapter, we review the recent history and the ultimate concepts that concern the materials application at device level. PSC were first described in 2009 and their reported efficiency quickly reached more than 24%. This unmatched efficiency evolution is accompanied by a potential cost reduction due to the ease of fabrication from solution processing. Also, the possibility of low temperature processing allows the use of flexible substrates that could include new markets that are unthinkable for other technologies. A global widespread of the PSC research helps understanding of the degradation and hysteresis issues that will in turn allow a near future commercial product. Respect to III–V materials, we witnessed the transition from the lattice matched structures to concepts that overcome the limits of the standard triple-junction cells. Graded lattice materials, named metamorphic (MM), allow bandgap engineering to optimize the solar spectrum match. Another concept explored to exceed the limits of lattice matched materials was the bonding of structures grown on different substrates. This conducted to the recent record obtained at module level in concentrating photovoltaics applications. Finally, design based on six junctions inverted MM achieved the last efficiency record of 47.1% at 143 suns. The cases considered in this chapter show two convergent strategies to improve the solar cell performance as an energy source: the potential of low cost at fairly competitive efficiencies for PSCs; and the high cell cost afforded by ultra-high efficiency of III–Vs under concentration. These emergent technologies are summoned as new actors in a world dominated by the well-established crystalline silicon technology.