Influence of Interfacial Reactions on Perovskite Optoelectronic Devices
small methods Wiley (2025) 2500438
Abstract:
Interfacial materials tend to alter the crystallization, films growth and defect formation process of the as‐deposited perovskites, which has been a critical and fundamental factor in determining the efficiency and operational stability of perovskite‐based optoelectronic devices. This review explores the underlying mechanism of interfacial reactions, which can either result in degradations or be beneficial. The influence of interfacial reactions, mainly interface‐induced deprotonation of organic cations and amidation processes, are discussed in relation to their impact on perovskite film growth and ensuing optoelectronic device performance. It is further proposed strategies to regulate these reactions and mitigate their negative effects to achieve high performance optoelectronic devices.Interfacial Energetics Reversal Strategy for Efficient Perovskite Solar Cells.
Advanced materials (Deerfield Beach, Fla.) (2025) e2503110
Abstract:
Reducing heterointerface nonradiative recombination is a key challenge for realizing highly efficient perovskite solar cells (PSCs). Motivated by this, a facile strategy is developed via interfacial energetics reversal to functionalize perovskite heterointerface. A surfactant molecule, trichloro[3-(pentafluorophenyl)propyl]silane (TPFS) reverses perovskite surface energetics from intrinsic n-type to p-type, evidently demonstrated by ultraviolet and inverse photoelectron spectroscopies. The reconstructed perovskite surface energetics match well with the upper deposited hole transport layer, realizing an exquisite energy level alignment for accelerating hole extraction across the heterointerface. Meanwhile, TPFS further diminishes surface defect density. As a result, this cooperative strategy leads to greatly minimized nonradiative recombination. PSCs achieve an impressive power conversion efficiency of 25.9% with excellent reproducibility, and a nonradiative recombination-induced qVoc loss of only 57 meV, which is the smallest reported to date in n-i-p structured PSCs.Inter‐Layer Diffusion of Excitations in 2D Perovskites Revealed by Photoluminescence Reabsorption
Advanced Functional Materials Wiley (2025)
Abstract:
<jats:title>Abstract</jats:title><jats:p>2D lead halide perovskites (2DPs) offer chemical compatibility with 3D perovskites and enhanced stability, which are attractive for applications in photovoltaic and light‐emitting devices. However, such lowered structural dimensionality causes increased excitonic effects and highly anisotropic charge‐carrier transport. Determining the diffusivity of excitations, in particular for out‐of‐plane or inter‐layer transport, is therefore crucial, yet challenging to achieve. Here, an effective method is demonstrated for monitoring inter‐layer diffusion of photoexcitations in (PEA)<jats:sub>2</jats:sub>PbI<jats:sub>4</jats:sub> thin films by tracking time‐dependent changes in photoluminescence spectra induced by photon reabsorption effects. Selective photoexcitation from either substrate‐ or air‐side of the films reveals differences in diffusion dynamics encountered through the film profile. Time‐dependent diffusion coefficients are extracted from spectral dynamics through a 1D diffusion model coupled with an interference correction for refractive index variations arising from the strong excitonic resonance of 2DPs. Such analysis, together with structural probes, shows that minute misalignment of 2DPs planes occurs at distances far from the substrate, where efficient in‐plane transport consequently overshadows the less efficient out‐of‐plane transport in the direction perpendicular to the substrate. Through detailed analysis, a low out‐of‐plane excitation diffusion coefficient of (0.26 ± 0.03) ×10<jats:sup>−4</jats:sup> cm<jats:sup>2</jats:sup> s<jats:sup>−1</jats:sup> is determined, consistent with a diffusion anisotropy of ≈4 orders of magnitude.</jats:p>Probing ionic conductivity and electric field screening in perovskite solar cells: a novel exploration through ion drift currents.
Energy & environmental science 18:3 (2025) 1385-1397
Abstract:
It is widely accepted that mobile ions are responsible for the slow electronic responses observed in metal halide perovskite-based optoelectronic devices, and strongly influence long-term operational stability. Electrical characterisation methods mostly observe complex indirect effects of ions on bulk/interface recombination, struggle to quantify the ion density and mobility, and are typically not able to fully quantify the influence of the ions upon the bulk and interfacial electric fields. We analyse the bias-assisted charge extraction (BACE) method for the case of a screened bulk electric field, and introduce a new characterisation method based on BACE, termed ion drift BACE. We reveal that the initial current density and current decay dynamics depend on the ion conductivity, which is the product of ion density and mobility. This means that for an unknown high ion density, typical in perovskite solar absorber layers, the mobility cannot be directly obtained from BACE measurements. We derive an analytical model to illustrate the relation between current density, conductivity and bulk field screening, supported by drift-diffusion simulations. By measuring the ion density independently with impedance spectroscopy, we show how the ion mobility can be derived from the BACE ion conductivity. We highlight important differences between the low- and high-ion density cases, which reveal whether the bulk electric field is fully screened or not. Our work clarifies the complex ion-related processes occurring within perovskite solar cells and gives new insight into the operational principles of halide perovskite devices as mixed ionic-electronic conductors.Determining Parameters of Metal-Halide Perovskites Using Photoluminescence with Bayesian Inference
PRX Energy American Physical Society (APS) 4:1 (2025) 13001