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Lead halide perovskites have prompted great interest, offering impressive photovoltaic performances. Most fundamental investigations and cell optimizations focus on solution‐based solar cells, which are not easily extended to larger scales. Commonly in these cells, losses in the open‐circuit voltage are attributed to arise primarily from interface recombination, and therefore the most studies have focused on optimization of the surface to eliminate defects states. In contrast, thermal evaporation is an alternative, solvent‐free, and scalable method to deposit lead halide perovskites that is gaining attention. However, the number of reports showing high‐efficiency solar cells (> 20%) prepared using thermal evaporation is still small. Here, the origins of non‐radiative charge carrier recombination are investigated in perovskite cells that are deposited via thermal co‐evaporation. This is done through a combination of photoluminescence spectroscopy, current‐voltage characterization, and simulations. It is found that the non‐radiative recombination in these cells is caused equally by bulk and interface defects. In general, it is advocated to perform a dual analysis of the photoluminescence spectroscopy of both the film and the photovoltaic device, in conjunction with current‐voltage measurements. It is emphasized that such a dual analysis is needed to enable the identification of improvements and to unlock further advancements in this technology. [ABSTRACT FROM AUTHOR]

Herein, the dehydration of a hydrogen molybdenum bronze (HYMoO3), converting it to molybdenum oxide (MoOX), is explored toward the development of perovskite solar cells (PSCs) for the first time. H0.11MoO3 bronze is synthesized, characterized, and deposited on indium tin oxide (ITO) under different concentrations and annealing conditions for in situ conversion into MoOX with appropriate oxygen vacancies. Vacuum‐deposited PSCs are fabricated using the as‐produced MoOX hole injection layers, achieving a power conversion efficiency of 17.3% (average) for the optimal device. The latter has its stability and reproducibility tested, proving the robustness and affordability of the developed hole transport layer in PSCs. [ABSTRACT FROM AUTHOR]

The photophysical dynamics of three complexes in the highly-emissive [Ir(pqi)2(NN)]+ series were investigated aiming at unique photophysical features and applications in light-emitting and singlet oxygen sensitizing research fields. Rational elucidation and Franck–Condon analyses of the observed emission spectra in nitrile solutions at 298 and 77 K reveal the true emissive nature of the lowest-lying triplet excited state (T1), consisting of a hybrid 3MLCT/LCIr(pqi)→pqi state. Emissive deactivations from T1 occur mainly by very intense, yellow-orange phosphorescence with high quantum yields and radiative rates. The emission nature experimentally verified is corroborated by theoretical calculations (TD-DFT), with T1 arising from a mixing of several transitions induced by the spin–orbit coupling, majorly ascribed to 3MLCT/LCIr(pqi)→pqi and increasing contributions of 3MLCT/LLCTIr(pqi)→NN. The microsecond-lived emission of T1 is rapidly quenched by molecular oxygen, with an efficient generation of singlet oxygen. Our findings show that the photophysics of [Ir(pqi)2(NN)][PF6] complexes is suitable for many applications, from the active layer of electroluminescent devices to photosensitizers for photodynamic therapy and theranostics. [ABSTRACT FROM AUTHOR]

In our search for light powered molecular devices, a novel fac-[Re(CO)3(ph2phen)(trans-stpyCN)]+ complex was synthesized to show switchable trans–cis configurations of the coordinated stpyCN ligand through efficient and reversible photoassisted isomerizations. Controlled photolyses of acetonitrile solutions led to spectral changes ascribed to reversible trans⇌cis photoisomerization processes. A remarkable quantum yield for the back cis-to-trans isomerization was obtained, with the same magnitude of the trans-to-cis photoprocess, and curiously, both trans- and cis-isomers are emissive at room temperature. Photochemical and photophysical characterization studies for fac-[Re(CO)3(ph2phen)(stpyCN)]+ provided insights into the isomerization and emissive light-driven pathways that are resulted from the interactions between the close-lying intraligand and charge transfer states. The reversible cis–trans photoisomerization has potential to be exploited as light-powered molecular motors and geometry regulators in molecular machines. [ABSTRACT FROM AUTHOR]

A novel Ir(iii) complex, [Ir(Fppy)2(Mepic)] (Fppy = 2-(2,4-difluorophenyl)pyridinate; Mepic = 3-methylpyridine-2-carboxylate) was engineered to show a blue phosphorescence with an impressive unitary quantum yield in our search for luminescent metal complexes for low cost displays and efficient lighting devices. Application of the Golden rule through Franck–Condon spectral analyses along with TD-DFT calculations and comparisons to the [Ir(Fppy)2(pic)] complex have provided insights on the mixing extension between charge-transfer (CT) and ligand-centered (LC) excited states in the emissive lowest-energy triplet transition for different media. The relatively narrow and vibronically-structured emission of [Ir(Fppy)2(Mepic)] at 298 K mainly arises from a spin–orbit-induced mixed 3MLCT-LCIr(Fppy)→Fppy/3LLCTFppy→Mepic excited state, with an enhanced MLCT character because of the methyl addition to pic. In frozen media at 77 K, the CT contribution is extinguished, leading to a pure LCFppy emission, with a similar emissive spectral profile to the free ligand, FppyH. The efficient blue emission shows that the complex is suitable for high-performance light-emitting devices and for thermo- and rigidity-sensors. [ABSTRACT FROM AUTHOR]

Vapor deposition of halide perovskites presents high potential for scalability and industrial processing of perovskite solar cells. It prevents the use of toxic solvents, allows thickness control, and yields conformal and uniform coating over large areas. However, the distinct volatility of the perovskite organic and inorganic components currently requires the use of multiple thermal sources or two‐step deposition to achieve the perovskite phase. In this work, single‐source, single‐step MA1–xFAxPbI3 thin film deposition with tunable stoichiometry by pulsed laser deposition is demostrated. By controlling the laser ablation of a solid target containing adjustable MAI:FAI:PbI2 ratios, the room temperature formation of cubic α‐phase MA1–xFAxPbI3 thin films is demonstrated. The target‐to‐film transfer of the ablated species, including the integrity of the organic molecules and the desired MA+:FA+ ratio, is confirmed by x‐ray photoelectron spectroscopy and solid‐state NMR. Photoluminescence analysis further confirms the shift of the bandgap with varying the MA+:FA+ ratio. Finally, proof‐of‐concept n‐i‐p solar cells with 14% efficiency are demonstrated with as‐deposited non‐passivated pulsed laser deposition (PLD)‐MA1–xFAxPbI3. This study opens the path for future developments in industry‐compatible vapor‐deposition methods for perovskite solar cells. [ABSTRACT FROM AUTHOR]

Organically modified mesoporous silica nanoparticles (MSNs) containing Ir complexes (Ir1, Ir2 and Ir3) were successfully synthesized. These Ir-entrapped MCM41-COOH nanoparticles have shown relevant photophysical characteristics including high efficiency in the photoproduction and delivery of singlet oxygen ( 1 O 2 ), which is particularly promising for photodynamic therapy (PDT) applications. In vitro tests have evidenced that complex@MCM41-COOH are able to reduce cell proliferation after 10 min of blue-light irradiation in Hep-G2 liver cancer cells., Competing Interests: Declaration of Competing Interest There are no conflicts of interest to declare., (Copyright © 2022 Elsevier B.V. All rights reserved.)

A variety of experiments on vacuum-deposited methylammonium lead iodide perovskite solar cells are presented, including JV curves with different scan rates, light intensity-dependent open-circuit voltage, impedance spectra, intensity-modulated photocurrent spectra, transient photocurrents, and transient voltage step responses. All these experimental data sets are successfully reproduced by a charge drift-diffusion simulation model incorporating mobile ions and charge traps using a single set of parameters. While previous modeling studies focused on a single experimental technique, we combine steady-state, transient, and frequency-domain simulations and measurements. Our study is an important step toward quantitative simulation of perovskite solar cells, leading to a deeper understanding of the physical effects in these materials. The analysis of the transient current upon voltage turn-on in the dark reveals that the charge injection properties of the interfaces are triggered by the accumulation of mobile ionic defects. We show that the current rise of voltage step experiments allow for conclusions about the recombination at the interface. Whether one or two mobile ionic species are used in the model has only a minor influence on the observed effects. A delayed current rise observed upon reversing the bias from +3 to -3 V in the dark cannot be reproduced yet by our drift-diffusion model. We speculate that a reversible chemical reaction of mobile ions with the contact material may be the cause of this effect, thus requiring a future model extension. A parameter variation is performed in order to understand the performance-limiting factors of the device under investigation.

In this work, efficient trans ⇌ cis photoswitchings of 4-(4-cyano)styrylpyridine (stpyCN) coordinated to organometallic bipyridyl tricarbonyl rhenium(I) complexes, fac-[Re(CO) 3 (NN)( trans-stpyCN)] + , where NN = 2,2'-bipyridine (bpy) or 4,4'-dimethyl-2,2'-bipyridine (dmb), are described. For both complexes, the true trans-to- cis quantum yields determined by 1 H NMR spectroscopy are similar at 313, 334, and 365 nm irradiations (Φ trans→ cis true(313-365 nm) ∼ 0.45), with a small decrease at 404 nm (Φ trans→ cis true(404 nm) ∼ 0.37). The investigated complexes also exhibit significant quantum yields for the reversible cis-to- trans photoreactions (Φ cis→ trans (255 nm) = 0.22). The luminescent properties of these complexes were also analyzed in different media to elucidate a key role of the 3 IL stpyCN state in photophysical and photochemical processes, giving new insights on their intriguing photobehavior.

A versatile Ru(II) complex bearing an anthracene moiety was synthesized in our search for suitable compounds towards efficient molecular devices. The new engineered dye, cis‑[Ru(dcbH 2 )(NCS) 2 (mbpy‑anth)] (dcbH 2 =2,2'‑bipyridyl‑4,4'‑dicarboxylic acid, mbpy‑anth=4‑[N‑(2‑anthryl)carbamoyl]‑4'‑methyl‑2,2'‑bipyridine), exhibits a blueish emission in a vibronically structured spectrum ascribed to the fluorescence of a 1 LC Anth (ligand centered) excited state in the anthracene and has a potential to be exploited in the fields of smart lighting and displays. This complex was also employed in dye-sensitized solar cells with fairly efficient solar energy conversion with the use of self-assembled TiO 2 compact layers beneath the TiO 2 mesoporous film to prevent meso‑TiO 2 /dye back reactions. Further photoelectrochemical investigations through incident photon-to-current efficiency and electrochemical impedance spectra showed that the all-nano-TiO 2 compact layer acts as contact layers that increase the electron harvesting in the external circuit, enhancing efficiencies up to 50%., (Copyright © 2018 Elsevier B.V. All rights reserved.)

In our search for light powered molecular devices, a novel fac-[Re(CO) 3 (ph 2 phen)(trans-stpyCN)] + complex was synthesized to show switchable trans-cis configurations of the coordinated stpyCN ligand through efficient and reversible photoassisted isomerizations. Controlled photolyses of acetonitrile solutions led to spectral changes ascribed to reversible trans⇌cis photoisomerization processes. A remarkable quantum yield for the back cis-to-trans isomerization was obtained, with the same magnitude of the trans-to-cis photoprocess, and curiously, both trans- and cis-isomers are emissive at room temperature. Photochemical and photophysical characterization studies for fac-[Re(CO) 3 (ph 2 phen)(stpyCN)] + provided insights into the isomerization and emissive light-driven pathways that are resulted from the interactions between the close-lying intraligand and charge transfer states. The reversible cis-trans photoisomerization has potential to be exploited as light-powered molecular motors and geometry regulators in molecular machines.