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Chemi-Structural Stabilization of Formamidinium Lead Iodide Perovskite by Using Embedded Quantum Dots
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posted on 2020-01-14, 13:07 authored by Sofia Masi, Carlos Echeverría-Arrondo, K. M. Muhammed Salim, Thi Tuyen Ngo, P. F. Mendez, Eduardo López-Fraguas, David F. Macias-Pinilla, Josep Planelles, Juan I. Climente, Iván Mora-SeróThe approaches to
stabilize the perovskite structure of formamidinium
lead iodide (FAPI) commonly result in a blue shift of the band gap,
which limits the maximum photoconversion efficiency. Here, we report
the use of PbS colloidal quantum dots (QDs) as a stabilizing agent,
preserving the original low band gap of 1.5 eV. The surface chemistry
of PbS plays a pivotal role by developing strong bonds with the black
phase but weak ones with the yellow phase. As a result, a stable perovskite
FAPI black phase can be formed at temperatures as low as 85 °C
in just 10 min, setting a record of concomitantly fast and low-temperature
formation for FAPI, with important consequences for industrialization.
FAPI thin films obtained through this procedure reach an open-circuit
potential (Voc) of 1.105 V, 91% of the
maximum theoretical Voc, and preserve
the efficiency for more than 700 h. These findings reveal the potential
of strategies exploiting the chemi-structural properties of external
additives to relax the tolerance factor and optimize the optoelectronic
performance of perovskite materials.