Interfacial Engineering through Chloride-Functionalized Self-Assembled Monolayers for High-Performance Perovskite Solar Cells

Abstract

The family of organic-inorganic hybrid perovskite (OIHPs) materials is one of the most promising for very high efficiency photovoltaic solar cells application. In the present work, the effect of a series of self-assembled monolayers placed at the TiO 2-perovskite junction, on the functioning of triple cation perovskite solar cells has been investigated. We show that employing 4-chlorobenzoic acid leads to the marked boosting of the solar cells performances. The starting pristine cell had a 20.3% power conversion efficiency (PCE) and the chemical engineering permitted to reach a PCE up to 21.35%. Our experimental study completed by density functional theory (DFT) calculations and modelling show that this improvement is due to the reduction of interfacial states, to the improvement of the quality of the OIHP material and to the structural continuity between TiO 2 and the OIHP. Especially, we demonstrate that the interfacial chemical interactions are important to consider in the design of highly efficient devices. Ultra 55 Zeiss FEG field-emission scanning electron microscope (FE-SEM) in the in-lens mode. The full experimental details are provided in the Supporting Information.

Applications of Self‐Assembled Monolayers for Perovskite Solar Cells Interface Engineering to Address Efficiency and Stability

“…[ 90 ] Similarly, Zhu et al. [ 86 ] have also utilized 4‐chlorobenzoic acid SAM on mesoporous TiO 2 and observed an increase in PCE from 20.3% to 21.35%. This improvement is caused by a charge transfer at the TiO 2 /perovskite interface induced by strong interfacial interactions, as demonstrated by density function theory (Figure 5f).…”

The Stabilization of Formamidinium Lead Tri‐Iodide Perovskite through a Methylammonium‐Based Additive for High‐Efficiency Solar Cells

“…In brief, the fluorine‐doped SnO 2 (FTO) substrates were cleaned and the compact TiO 2 hole blocking layer ( c ‐TiO2) and the mesoporous TiO 2 ( mp ‐TiO 2 ) layer were deposited, as described in a previous study. [ 17 ] We prepared a mixed cation precursor solution with a 1.2 m concentration by mixing 206 mg of formamidinium iodide (FAI, greatcell), 553 mg of PbI 2 (TCI), and 16.2, 24.3, 32.4, 38.9, and 44.6 mg of methylammonium chloride (Alfa Aesar) in 800 μL DMF and 200 μL DMSO. They corresponded to 20, 30, 40, 48, and 55 mol% of FAI, respectively.…”

“…Spiro‐OMeTAD (Borun New Material Technology) was used as the hole transporting material and prepared, as detailed in a previous study. [ 17 ] The solar cells characterizations, the XRD patterns, the absorbance, and PL spectra measurements as well as the Tauc plot analyses of the films were carried out as described in our previous work. [ 17 ] A Quantax system from Bruker operated at 15 kV was used for the EDX spectra measurements.…”

“…The stabilization of the photoactive black perovskite α-phase requires the incorporation of an extra monovalent cation. [6,17] To the best of our knowledge and as shown in Table S1, Supporting Information, PSCs reaching PCE > 22% reported in the literature contain methylammonium (MA þ ) as an extra-organic cation. [10][11][12][13][14][15] However, the presence of MA þ presents disadvantages as this organic compound is hydrophilic and its excess can be degassed out of the layer.…”

Perovskite Nano‐Heterojunctions: Synthesis, Structures, Properties, Challenges, and Prospects

“…[217] Later on, many perovskite heterojunction-based SAMs were investigated. [218][219][220][221][222] The well-aligned SAMs between the heterojunctions would produce a permanent molecular dipole moment, which can be directed toward or away from the perovskite. In the former condition, the work function of the contacted metal or oxide semiconductor decreases, favoring the extraction of the photogenerated charges (electrons) from the perovskite.…”