Enhanced Open-Circuit Voltage of PbS Nanocrystal Quantum Dot Solar Cells

• Published in: Scientific reports Vol. 3; no. 1; p. 2225
• Main Authors: Yoon, Woojun, Boercker, Janice E., Lumb, Matthew P., Placencia, Diogenes, Foos, Edward E., Tischler, Joseph G.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 19-07-2013; Nature Publishing Group
• Subjects: 639/166/987; 639/301/299/946; 639/624/399/1017; 639/925/927/1007; Absorbance; Electric Power Supplies; Humanities and Social Sciences; Illumination; Lead - chemistry; multidisciplinary; Nanocrystals; Photovoltaic cells; Quantum dots; Quantum Dots - chemistry; Recombination; Science; Solar Energy; Sulfides - chemistry; Thermodynamics; Voltage
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep02225

Nanocrystal quantum dots (QD) show great promise toward improving solar cell efficiencies through the use of quantum confinement to tune absorbance across the solar spectrum and enable multi-exciton generation. Despite this remarkable potential for high photocurrent generation, the achievable open-circuit voltage (
V
oc
) is fundamentally limited due to non-radiative recombination processes in QD solar cells. Here we report the highest open-circuit voltages to date for colloidal QD based solar cells under one sun illumination. This
V
oc
of 692 ± 7 mV for 1.4 eV PbS QDs is a result of improved passivation of the defective QD surface, demonstrating
as a function of the QD bandgap (
E
g
). Comparing experimental
V
oc
variation with the theoretical upper-limit obtained from one diode modeling of the cells with different
E
g
, these results clearly demonstrate that there is a tremendous opportunity for improvement of
V
oc
to values greater than 1 V by using smaller QDs in QD solar cells.