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Research in the field of organic electronics has witnessed dramatic improvements in device performance over the past several decades through an ever‐improving understanding of electron and hole movement and the development of new interfacial materials. In this study, a type of interfacial material that relies on ionic charges comprising metal:poly(styrenesulfonate) (PSS) polyelectrolytes are synthesized and investigated as structural analogs of the ubiquitously used poly(3,4‐ethylenedioxythiophene:polystyrenesulfonate) (PEDOT:PSS) hole transport layer, in order to investigate correlations between metal cation ions and the cationic PEDOT component. The metal ions selected for this study include Li, Mg, V, Mn, Co, Ni, Cu, Zn, Pd, Ag, Cs, and Pb ions. To analyze the interfacial energy level alignment, electronic band structure, and band bending at the Indium tin oxide (ITO)/metal:PSS interface, X‐ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS) are employed. Alkali (earth) and post‐transition metals show deep highest occupied molecular orbital (HOMO) levels and low work function (WF) due to Fermi level balance, implying poor hole transport. Remarkably, Cu:PSS displays a unique electronic structure, suggesting potential as a hole transport layer with increased WF and low hole injection barrier. Period 5 transition metals mirror PEDOT:PSS trends, and Ag:PSS holds the potential to form effective ohmic contacts. [ABSTRACT FROM AUTHOR]

Controlling the formation of photoexcited triplet states is critical for many (photo)chemical and physical applications. Here, we demonstrate that a permanent out‐of‐plane distortion of the benzothioxanthene imide (BTI) dye promotes intersystem crossing by increasing spin‐orbit coupling. This manipulation was achieved through a subtle chemical modification, specifically the bay‐area methylation. Consequently, this simple yet efficient approach expands the catalog of known molecular engineering strategies for synthesizing heavy atom‐free, dual redox‐active, yet still emissive and synthetically accessible photosensitizers. [ABSTRACT FROM AUTHOR]

Despite achieving high efficiencies over a short time, further streamlining of hybrid lead‐halide perovskite solar cell (PSC) designs is necessary for their commercial viability. In this contribution, a new class of interfacial hole transporting layer (HTL) materials consisting of anionic polyelectrolytes comprising polystyrene sulfonate (PSS) with metal cations are explored. These materials represent alternatives to metal oxides, combining characteristics of metal oxides with the facile preparation and desirable film‐forming characteristics of polyelectrolytes. Polyelectrolytes with cations including Li, Mg, V, Mn, Co, Ni, Cu, Zn, Pd, Ag, In, Cs, and Pb as HTLs in inverted PSCs are explored. A range of positive and negative effects is observed for different metal cations, which are attributed to differences in the physical properties of the polyelectrolytes, and their influence on the electronic band structure of devices and the crystal qualities of the perovskite absorber. Ni and Cu polyelectrolytes created p‐type contacts at the anode of PSCs, improving device performance. These materials are believed to have potential in other types of devices as well. This type of metal:PSS polyelectrolyte has not yet been widely investigated, however, it is shown that it constitutes a simple and economic strategy to engineer energy band structures in perovskite devices. [ABSTRACT FROM AUTHOR]

Hybrid organic–inorganic perovskites (HOIPs) have attracted considerable attention for their scientific and technological potential in photovoltaics and optoelectronic devices. Recently, two-dimensional (2D) HOIPs have become established as useful active layers for photovoltaic applications, offering adjustable electronic levels, high charge carrier mobilities, and simplicity of thin-film device fabrication. In this work, we describe the preparation of a new Cu-based 2D hybrid perovskite, with the structural formula (C6H10N2)[CuCl4], of which crystallographic, spectroscopic, optical and magnetic properties have been studied and analyzed. The compound exhibits dominant ferromagnetic interactions. Fits of the χ(T) data to the 2D-ferromagnetic layer model yielded C = 0.456(2) emu-K mol-Oe−1 and J = 5.5(1). Analysis of electromagnetic absorption and reflectance properties through the visible and near-infrared indicate an optical band gap of 1.24 eV (absorption) or 1.23 eV (reflection) and a direct, spin-forbidden electronic transition giving rise to a strong absorption band centered at 740 nm, which allows it to absorb a large portion of the solar spectrum. Although the absorption coefficient is lower than lead halide perovskites, it is greater than 1000 cm−1 throughout the visible spectrum up to 1000 nm, giving the material potential as a solar absorber if relatively thick (∼5 μm) films are used. The nature of the electronic transition and frontier electronic states were studied by DFT and reveal valence and conduction bands arising from repeating CuCl4 square planar structural units composed of hybridized Cl 3px,y orbitals and Cu 3dx2−y2 orbitals. The electronic structure and optical properties indicate that the material might be able to serve as a non-toxic alternative to lead-based HOIPs in some applications. [ABSTRACT FROM AUTHOR]

Despite the exceptional efficiency of perovskite solar cells (PSCs), further improvements can be made to bring their power conversion efficiencies (PCE) closer to the Shockley‐Queisser limit, while the development of cost‐effective strategies to produce high‐performance devices are needed for them to reach their potential as a widespread energy source. In this context, there is a need to improve existing charge transport layers (CTLs) or introduce new CTLs. In this contribution, we introduced a new polyelectrolyte (lithium poly(styrene sulfonate (PSS))) (Li:PSS) polyelectrolyte as an HTL in inverted PSCs, where Li+ can act as a counter ion for the PSS backbone. The negative charge on the PSS backbone can stabilize the presence of p‐type carriers and p‐doping at the anode. Simple Li:PSS performed poorly due to poor surface coverage and voids existence in perovskite film as well as low conductivity. PEDOT:PSS was added to increase the conductivity to the simple Li:PSS solution before its use which also resulted in lower performance. Furthermore, a bilayer of PEDOT:PSS and Li:PSS was employed, which outperformed simple PEDOT:PSS due to high quality of perovskite film with large grain size also the large electron injection barrier (ϕe) impeded back diffusion of electrons towards anode. As a consequence, devices employing PEDOT:PSS / Li:PSS bilayers gave the highest PCE of 18.64%. [ABSTRACT FROM AUTHOR]

This article, titled "Driving Triplet State Population in Benzothioxanthene Imide Dyes: Let's twist!" explores a chemical modification technique that induces a permanent out-of-plane distortion in the π-conjugated backbone of a benzothioxanthene imide (BTI). The researchers found that this strategy effectively manipulates triplet formation and provides insights into the connection between spin-orbit coupling, twisting of the π-system, and intersystem crossing. The full research article provides more detailed information on this topic. [Extracted from the article]

The interaction between ionic moieties and the electronic properties of organic and hybrid semiconductors can yield a variety of interesting and sometimes surprising effects. Ionic moieties can induce interface dipoles, support electrochemical doping and lead to band-bending. The dynamic motion of ions under electric fields and the induced changes in conductivity can make it difficult to de-convolute the various mechanisms at play. This review attempts to provide a perspective on different types of interactions between ions and semiconductors and goes into depth addressing the application of solution-processed polyelectrolyte and oligoelectrolyte materials to control the energy band structures and behaviour of organic and hybrid semiconducting optoelectronic devices. This review introduces and highlights different types of ionic materials (such as conjugated polyelectrolytes and molecular ionic dopants) that have been used to achieve different effects (such as creating interfacial dipoles, vacuum energy shifts, changes in Fermi energies and doping) in organic and hybrid semiconducting devices before going into greater depth with the emerging class of non-conjugated polyelectrolytes and oligoelectrolytes and provides a comprehensive summary of recent progress using these materials in semiconducting devices. This class of materials has been receiving increasing attention recently and provides insights into the fundamental effects of ionic functionalities on the energy band structures and functions in organic and hybrid semiconductors. [ABSTRACT FROM AUTHOR]

We've observed intense fluorescence from the surface of lead formate crystals when they are precipitated from a CH3NH3PbBr3 (MAPbBr3) perovskite precursor solution. The crystals exhibit emission in the range of 500–550 nm with a photoluminescence quantum yield (PLQY) of up to 70%. The fluorescence is stable in water and at elevated temperature without significant decrease in PLQY for months, conditions which instantly decompose MAPbBr3. Fluorescence occurred with the highest quantum efficiency of 70% at an optimal 1 : 0.3 molar ratio of methylammonium formate and lead bromide and decreased rapidly for other ratios. Fluorescence was quenched using other halides (Cl or I) or other cations (Cs, ethylammonium, propylammonium, etc.). Single crystal analysis indicates that the material possesses the lead formate structure with lattice parameters which are identical to pristine lead formate, however, analysis of the particles by EDX, XPS and fluorescence microscopy confirms the presence of Br and fluorescence emission on the particle surfaces. The observed material characteristics indicate that the emissive species consists of a mixed-valence surface layer of Pb coordinated to both Br and formate ligands. [ABSTRACT FROM AUTHOR]

By virtue of the exceptional optical and electrical features of organic-inorganic lead-halide perovskites, the power conversion efficiency (PCE) of perovskite solar cells (PeSCs) has surpassed that of commercialized single junction silicon solar cells. Although PeSCs have demonstrated exceptional efficiency, there is still room for improvement to approach the theoretical Shockley-Queisser limit. Additionally, there is a need for the development of cost-effective strategies to produce high-performance devices, enabling PeSCs to fulfill their potential as a widely adopted and sustainable energy source. Considering this, in this work, we've developed a polyelectrolyte (silver poly(styrene sulfonate (PSS)) (Ag:PSS) hole transport layer (HTL), and investigated it in combination with a conjugated polymer,poly[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5- b ]-dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4- b ]thiophenediyl] (PTB7) as a bilayer HTL. Ag:PSS alone performs poorly due to mismatched energy levels at the anode interface, however, when PTB7 is used in combination with Ag:PSS, effective extraction and transport of carriers towards the anode is achieved. PeSCs with optimized bilayer HTLs (Ag:PSS/PTB7) gave PCEs of up to 17.09 %, higher than that of the Ag:PSS alone (reference device 12.13 %) which can be attributed to improved interfacial energetics at the HTL/perovskite interface. • The effectiveness of a hole transport bilayer were comprised a polyelectrolyte-based Ag:PSS with a p-type conjugated polymer (PTB7). • While single-layer Ag:PSS underperformed due to poor surface coverage and voids in the perovskite film. • The bilayer-based perovskite solar cells exhibited a maximum PCE of 17.09% and maximum VOC of 1.05 V. [ABSTRACT FROM AUTHOR]