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Mixed Lead Halide Passivation of Quantum Dots
Author(s) -
Fan James Z.,
Andersen Nigel T.,
Biondi Margherita,
Todorović Petar,
Sun Bin,
Ouellette Olivier,
Abed Jehad,
Sagar Laxmi K.,
Choi MinJae,
Hoogland Sjoerd,
de Arquer F. Pelayo García,
Sargent Edward H.
Publication year - 2019
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.201904304
Subject(s) - passivation , halide , materials science , photovoltaics , perovskite (structure) , optoelectronics , quantum dot , iodide , nanotechnology , inorganic chemistry , photovoltaic system , chemistry , layer (electronics) , crystallography , electrical engineering , engineering
Infrared‐absorbing colloidal quantum dots (IR CQDs) are materials of interest in tandem solar cells to augment perovskite and cSi photovoltaics (PV). Today's best IR CQD solar cells rely on the use of passivation strategies based on lead iodide; however, these fail to passivate the entire surface of IR CQDs. Lead chloride passivated CQDs show improved passivation, but worse charge transport. Lead bromide passivated CQDs have higher charge mobilities, but worse passivation. Here a mixed lead‐halide (MPbX) ligand exchange is introduced that enables thorough surface passivation without compromising transport. MPbX–PbS CQDs exhibit properties that exceed the best features of single lead‐halide PbS CQDs: they show improved passivation (43 ± 5 meV vs 44 ± 4 meV in Stokes shift) together with higher charge transport (4 × 10 ‐2 ± 3 × 10 ‐3 cm 2 V ‐1 s ‐1 vs 3 × 10 ‐2 ± 3 × 10 ‐3 cm 2 V ‐1 s ‐1 in mobility). This translates into PV devices having a record IR open‐circuit voltage (IR V oc ) of 0.46 ± 0.01 V while simultaneously having an external quantum efficiency of 81 ± 1%. They provide a 1.7× improvement in the power conversion efficiency of IR photons (>1.1 µm) relative to the single lead‐halide controls reported herein.