Efficient and Stable PbS Quantum Dot Solar Cells by Triple-Cation Perovskite Passivation

TL;DR

This study demonstrates that triple-cation perovskite passivation of PbS quantum dots significantly enhances solar cell efficiency and stability, achieving 11.3% efficiency and maintaining performance over 1200 hours.

Contribution

It introduces a novel triple-cation perovskite passivation method that improves efficiency and stability of PbS quantum dot solar cells compared to previous ligand-based approaches.

Findings

Achieved 11.3% power conversion efficiency.

Maintained 96% performance after 1200 hours.

Confirmed perovskite shell formation around PbS nanocrystals.

Abstract

Solution-processed quantum dots (QDs) have a high potential for fabricating low cost, flexible and large-scale solar energy harvesting devices. It has recently been demonstrated that hybrid devices employing a single monovalent cation perovskite solution for PbS QD surface passivation exhibit enhanced photovoltaic performance when compared to standard ligand passivation. Herein we demonstrate that the use of a triple cation Cs0.05(MA0.17FA0.83)0.95Pb(I0.9Br0.1)3 perovskite composition for surface passivation of the quantum dots results in highly efficient solar cells, which maintain 96 % of their initial performance after 1200h shelf storage. We confirm perovskite shell formation around the PbS nanocrystals by a range of spectroscopic techniques as well as high-resolution transmission electron microscopy. We find that the triple cation shell results in a favorable energetic alignment to the core of the dot, resulting in reduced recombination due to charge confinement without limiting transport in the active layer. Consequently, photovoltaic devices fabricated via a single-step film deposition reached a maximum AM1.5G power conversion efficiency of 11.3 % surpassing most previous reports of PbS solar cells employing perovskite passivation.