Issue 33, 2013

High performance PbS Quantum Dot Sensitized Solar Cells exceeding 4% efficiency: the role of metal precursors in the electron injection and charge separation

Abstract

Here we report the preparation of high performance Quantum Dot Sensitized Solar Cells (QDSCs) based on PbS–CdS co-sensitized nanoporous TiO2 electrodes. QDs were directly grown on the TiO2 mesostructure by the Successive Ionic Layer Absorption and Reaction (SILAR) technique. This method is characterized by a fast deposition rate which involves random crystal growth and poor control of the defect states and lattice mismatch in the QDs limiting the quality of the electrodes for photovoltaic applications. In this work we demonstrate that the nature of the metallic precursor selected for SILAR has an active role in both the QD's deposition rate and the defect's distribution in the material, with important consequences for the final photovoltaic performance of the device. For this purpose, acetate and nitrate salts were selected as metallic precursors for the SILAR deposition and films with similar absorption properties and consequently with similar density of photogenerated carriers were studied. Under these conditions, ultrafast carrier dynamics and surface photovoltage spectroscopy reveal that the use of acetate precursors leads to higher injection efficiency and lower internal recombination due to contribution from defect states. This was corroborated in a complete cell configuration with films sensitized with acetate precursors, achieving unprecedented photocurrents of ∼22 mA cm−2 and high power conversion efficiency exceeding 4%, under full 1 sun illumination.

Graphical abstract: High performance PbS Quantum Dot Sensitized Solar Cells exceeding 4% efficiency: the role of metal precursors in the electron injection and charge separation

Supplementary files

Article information

Article type
Paper
Submitted
18 Apr 2013
Accepted
18 Apr 2013
First published
19 Apr 2013

Phys. Chem. Chem. Phys., 2013,15, 13835-13843

High performance PbS Quantum Dot Sensitized Solar Cells exceeding 4% efficiency: the role of metal precursors in the electron injection and charge separation

V. González-Pedro, C. Sima, G. Marzari, P. P. Boix, S. Giménez, Q. Shen, T. Dittrich and I. Mora-Seró, Phys. Chem. Chem. Phys., 2013, 15, 13835 DOI: 10.1039/C3CP51651B

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