Manipulating Electron Density Distribution of Nicotinamide Derivatives Toward Defect Passivation In Perovskite Solar Cells

Abstract

The design of additives mainly involves selection of functional groups with coordination relationships with defects in perovskite materials. However, it is particularly important to further adjust the geometrical configuration and electronic structure of an additive. Here, the nicotinamide (NA) and its derivative 6‐Methylnicotinamide (CNA) with electron‐donor functional groups are comparatively analyzed to investigate the effect of molecular dipole and electronic configuration on the defect passivation of perovskite absorbers and the photovoltaic properties of perovskite solar cells (PSCs). Theoretical calculations demonstrate that the CNA molecule with its large molecular dipole combine with the undercoordinated Pb2+ ions in perovskite to form a higher binding energy, which is beneficial to improve the formation energy of Pb‐related defects. Experimental characterization confirms that the CNA molecule significantly enhances the coordination effect between acylamino and undercoordinated defective Pb2+ cations, which is conducive to obtain high‐quality, low‐defect density of state, large grain size, and smooth surface perovskite absorbers. Thanks to the electronic configuration and electronic cloud distribution of CNA molecules, the PSCs yield impressive efficiency as high as 24.33% with excellent environmental storage, heat, and light stabilities. This research provides a research basis for designing additives with steric‐charge‐dependence to assist perovskite photovoltaics.

Flexible Backbone-Assisted Green-Solvent Processable Polymer Hole Transport Material in Perovskite Solar Cells

“…By contrast, a similar obvious shift is not observed for the PTAA-based perovskite substrate. This shift toward the low-energy region in Pb 4f could arise out of the interaction of carbonyl groups and sulfur atoms of A-EDOT with uncoordinated Pb ions via CO···Pb and S···Pb chelation. ,, Figure d confirms the O 1s spectra of CO, in which the peak of the A-EDOT/perovskite appears at 532.4 eV, while it appears at 532.2 eV for the pristine A-EDOT film. The offsets of O 1s and Pb 4f peaks manifest that the CO strongly coordinated with Pb 2+ , which agrees with the FTIR result.…”

A Binary Solution Strategy Enables High-Efficiency Quasi-2D Perovskite Solar Cells with Excellent Thermal Stability

“…Both FTIR peaks of the CO bond in the perovskite films present a red-shift tendency, which indicates the interaction between perovskites and solvents. These observations may be linked to the coordination between the CO bond of HAc and DMF and PbI 2 , eventually resulting in an electronic rearrangement between the solvents and perovskite components, such that the vibrational frequencies of the CO bond decrease. , …”

“…These observations may be linked to the coordination between the C�O bond of HAc and DMF and PbI 2 , eventually resulting in an electronic rearrangement between the solvents and perovskite components, such that the vibrational frequencies of the C�O bond decrease. 18,44 Recently, the presence of energetic cascades in quasi-2D perovskites was identified. 45,46 The peculiar phase alignment (on the order of n = 2, 3, 4, and ∞ along the film depth direction) can facilitate the transport of photocarriers in the 2D PSC.…”

Synergistic Defect Passivation and Crystallization Modulation in Efficient Perovskite Solar Cells: The Case of Multifunctional 2-Anisidine-4-Sulfonic Acid

“…To adequately settle the above-mentioned problems, enormous efforts have been taken toward the development of various passivation materials to heal imperfections, modulate perovskite crystallization and improve the efficiency and stability of PSCs. − Additive engineering has been known as a feasible and effective method to passivate defect sites and directly regulate the morphology of perovskite for fabricating high-crystallinity, low-defect-density, large-size-grain perovskite film. − In the early studies, a series of monofunctional Lewis bases mediators with O and N heteroatoms such as PMMA, quinoline and pyrrole have been successfully adopted to chelate with uncoordinated Pb 2+ , which was believed as the main source of charge traps . For example, Li et al employed the quinoline with the intention of passivating the internal defects of perovskite, where the nitrogen atom anchors the uncoordinated Pb 2+ via coordinate bond, thereby neutralizing the excess positive charge in the crystal .…”