Solution-processed colloidal quantum dot photovoltaics: A perspective

Abstract

Deployed solar cells today are predominantly first-generation devices based on silicon. Single-crystal materials offer the advantage of high efficiency, but costs associated with materials, manufacturing, and installation remain high. Second generation, or thin-film, technologies, such as those based on CdTe and CuInGaSe2, offer dramatically improved costs per square meter, but at the price of lower efficiencies. Third-generation photovoltaics aspire to unite high efficiency with low cost. Strategies include nanostructured semiconductors, inorganic‐organic hybrid structures, and molecular assemblies. Solution-processed colloidal quantum dot (CQD) photovoltaic devices offer considerable promise as a third-generation photovoltaic candidate. Their solution-synthesis and -coating offer a path to low-cost roll-to-roll manufacturing atop flexible, lightweight substrates. The bandgap of CQDs is tuned via the nanoparticles’ diameter, allowing them to absorb the sun’s broad visible and infrared spectrum within a single materials-processing strategy. CQD photovoltaics have, with only a half-decade’s intense activity, reached above 5% solar power conversion efficiency, 1,2 and progress shows no signs of abating. Here we review the latest advances in the field and discuss the avenues for further progress towards commercially compelling performance. We include a discussion of the materials themselves, considering their synthesis and their photophysical properties. We review briefly the fundamentals of semiconductors and solar cells. We highlight the major progress and achievements in CQD photovoltaics, focusing on the introduction of improved device architectures.