Synergistic Buried Interface Regulation of Tin-Lead Perovskite Solar Cells via Co-Self-Assembled Monolayers.

Tin-lead (Sn-Pb) perovskite solar cells (PSCs) hold considerable potential for achieving efficiencies near the Shockley-Queisser (S-Q) limit. Notably, the inverted structure stands as the preferred fabrication method for the most efficient Sn-Pb PSCs. In this regard, it is imperative to implement a strategic customization of the hole selective layer to facilitate carrier extraction and refine the quality of perovskite films, which requires effective hole selectivity and favorable interactions with Sn-Pb perovskites. Herein, we propose the development of Co-Self-Assembled Monolayers (Co-SAM) by integrating both [2-(9H-carbazol-9-yl)ethyl]phosphonic acid (2PACz) and glycine at the buried contacts. The one-step deposition process employed in the fabrication of the Co-SAM ensures uniform coverage, resulting in a homogeneous surface potential. This is attributed to the molecular interactions occurring between 2PACz and glycine in the processing solution. Furthermore, the amine (-NH2) and ammonium (-NH3+) groups in glycine effectively passivate Sn4+ defects at the buried interface of Sn-Pb perovskite films, even under thermal stress. Consequently, the synergistic buried interface regulation of Co-SAM leads to a power conversion efficiency (PCE) of 23.46%, which outperforms devices modified with 2PACz or glycine alone. The Co-SAM-modified Sn-Pb PSC demonstrates enhanced thermal stability, maintaining 88% of its initial PCE under 65 °C thermal stress for 590 h.

Systematic investigation of coupling between symmetric and antisymmetric stretches of D2O in CHCl3 by 2D IR.

The coupling between the symmetric (νs) and antisymmetric (νa) OD stretch modes of monomeric D2O in CHCl3 is investigated using polarization-dependent two-dimensional infrared (2D IR) spectroscopy supported by numerical 2D IR simulations based on the exciton-band theory. The relationship between the local modes' and the exciton states' parameters is systematically studied, including center frequencies, diagonal anharmonicities, coupling, and off-diagonal anharmonicity. The mean coupling between νs and νa is accurately evaluated to be -49.96 ± 0.14 cm-1. The degree of relaxation in the harmonic approximation is quantified, and the angle between the exciton-state dipoles is accurately evaluated to be 101.4° ± 3.6°. In addition, the effect of the local-mode frequency correlation on the resulting exciton-state frequency correlation and the spectral shape of the linear and 2D IR spectra are also investigated.

Scattering Elimination of Heterodyne-Detected Two-Dimensional Infrared Spectra Using Choppers and Shutters.

Obtaining high-quality 2D IR spectra of heterogeneous samples such as perovskite films or metal-organic framework powder is hampered by severe light scattering. In the pump-probe (PP) method, this problem can be circumvented by phase cycling. However, in the heterodyned photon echo (HPE) method, phase cycling does not function as effectively as the PP method. This study demonstrates that the scattering problem can be solved mechanically by introducing another chopper and two shutters into the existing 2D IR setup without moving any translation stages to introduce a phase shift in the HPE method. For a perovskite film having a very rough surface, containing a small amount of residual dimethylformamide, and having a maximum absorbance of ∼0.0004 in the C═O stretch region, this advanced experimental method is tested and proven to be highly effective.