ED6: Nanostructured Quantum-Confined Materials for Advanced Optoelectronics
I captured too much enthusiasm

ED6: Nanostructured Quantum-Confined Materials for Advanced Optoelectronics

Maria Antonietta Loi, University of Groningen

PbS QD Solar Cells—The Open Circuit Voltage Problem

Written by Ahmad R. Kirmani

An important parameter holding back the entry of colloidal quantum dots (CQDs) solar cells into the flexible optoelectronics market has been the open-circuit voltage (VOC) problem. VOC is a key parameter in determining solar cell performance and is impacted by the surface defects that the CQDs, unfortunately, have in abundance owing to their large surface-to-volume ratio. Understandably therefore, it has been to good effect that the community has focused attention on surface passivation strategies. These efforts have seen the CQD solar cells skyrocket from 1% to 12% power-conversion-efficiencies (PCEs) over the decade.

Maria Loi’s group at the University of Groningen has been interested in obtaining a fundamental understanding of what governs traps and how this scourge can be put to rest. An important recent contribution by the group includes the demonstration that the VOC values increase at lower solar cell operation temperatures, giving key insights into the nature of these surface traps. These insights have recently helped the Loi group to suggest that in the pn junction of these heterjunction solar cells, the p-layers are usually insufficiently doped. Clear device performance improvements are observed upon increasing the hole concentration in these layers. These results provide crucial design rules for CQD photovoltaics and are an important step toward solving the voltage problem.

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