Ultraviolet-Filtering Luminescent Transparent Coatings for High-Performance PTB7-Th:ITIC–Based Organic Solar Cells

Photovoltaic (PV) devices based on organic heterojunctions have recently achieved remarkable power conversion efficiency (PCE) values. However, photodegradation is often a cause of dramatic drops in device performance. The use of ultraviolet (UV)-absorbing luminescent downshifting (LDS) layers can be a mitigation strategy to simultaneously filter UV radiation reaching the device and reemit it with lower energy in the visible spectral range, matching the maximum spectral response of the PV cells and thus enabling the increase of the photocurrent generated by the cell. In this work, we report the use of a Eu3+-doped siliceous-based organic–inorganic hybrid as a coating on organic solar cells based on the PTB7-Th:ITIC bulk heterojunction with the purpose of increasing their performance. We found that the applied coatings yield a PCE enhancement of ∼22% (from 3.1 to 3.8%) in solar cells with spin-coated layers, compared with the bare solar cells, which is among the highest performance enhancements induced by plastic luminescent coatings.

Luminescent phosphine copper(i) complexes with various functionalized bipyridine ligands: synthesis, structures, photophysics and computational study

A new series of luminescent phosphine copper(i) complexes with cyano- and hydroxyl-substituted 2,2′-bipyridine ligands have been synthesized and structurally characterized. Their luminescent properties have also been investigated in detail.

Polynuclear Cu(i) and Ag(i) phosphine complexes containing multi-dentate polytopic ligands: syntheses, crystal structures and photoluminescence properties

A series of polynuclear metal complexes, [Cu2(L1)(PPh3)4](ClO4)2 (1), [Cu3(L2)(PPh3)6](ClO4) (2), [Cu3(L3)(PPh3)6] (3), [Ag2(L1)(PPh3)4](BF4)2 (4), [Ag4(L2)2(PPh3)6] (5) and [Ag3(L3)(PPh3)5] (6), have been obtained from the reactions of the highly conjugated bridging ligands 2,3-bis(2-pyridyl)pyrazine (L1), 2,3-bis(2-tetrazoyl)pyrazine (H2L2) and 2,3-bis(2-tetrazoyl)imidazole (H3L3) with [Cu(MeCN)4]ClO4 and AgBF4, respectively. Their crystal structures have been determined by X-ray crystallography and their photophysical properties have been investigated in detail. Complexes 1 and 3 show photoluminescence in CH2Cl2 solution, while all the complexes exhibit obvious luminescence in the solid state; detailed photophysical studies and density functional theory calculations of these complexes have revealed that their lowest energy absorptions and emissions are predominantly derived from either metal-to-ligand charge-transfer (MLCT) or intraligand (IL) excited states.

Self-assembly of heteroleptic dinuclear silver(i) complexes bridged by bis(diphenylphosphino)ethyne

We present a study of the self-assembling behaviour in solution of Ag[PF₆] with one equivalent of an N^N ligand (N^N = 6,6'-dimethyl-2,2'-bipyridine (6,6'-Me₂bpy) or 2,2':6',2''-terpyridine (tpy)), together with either 0.5 or one equivalent of the bridging ligand bis(diphenylphosphino)ethyne (dppa). Each product contains a dinuclear cation, with one or two dppa ligands bridging the two Ag⁺ centres; 6,6'-Me₂bpy and tpy, respectively, act as chelating ligands. The compounds have been analysed in solution using NMR spectroscopic methods (¹H, ¹H{³¹P}, COSY, NOESY, ¹³C, HMQC and HMBC), including room and low temperature measurements. ³¹P{¹H} NMR spectra recorded at different temperatures allow a deeper insight into the dynamic equilibrium processes. In addition, solution ³¹P-¹⁰⁹Ag HSQC spectroscopic measurements were performed and show, inter alia, the ratio of the splitting in the F1 dimension and the ¹J_{³¹P-¹⁰⁹Ag} coupling constant in the fully coupled HSQC. Single crystal X-ray diffraction yielded two pseudo-polymorphic structures for the doubly-bridged [Ag₂(dppa)₂(tpy)₂][PF₆]₂ and one for the singly-bridged [Ag₂(dppa)(6,6'-Me₂bpy)₂][PF₆]₂.

Towards Efficient Spectral Converters through Materials Design for Luminescent Solar Devices

Single-junction photovoltaic devices exhibit a bottleneck in their efficiency due to incomplete or inefficient harvesting of photons in the low- or high-energy regions of the solar spectrum. Spectral converters can be used to convert solar photons into energies that are more effectively captured by the photovoltaic device through a photoluminescence process. Here, recent advances in the fields of luminescent solar concentration, luminescent downshifting, and upconversion are discussed. The focus is specifically on the role that materials science has to play in overcoming barriers in the optical performance in all spectral converters and on their successful integration with both established (e.g., c-Si, GaAs) and emerging (perovskite, organic, dye-sensitized) cell types. Current challenges and emerging research directions, which need to be addressed for the development of next-generation luminescent solar devices, are also discussed.

Luminescent diphosphine fluorophenylthiolate silver(i) compounds that exhibit argentophilic interactions

Relatively small changes in the fluorophenylthiolate ligand of silver(i) bidentate phosphine compounds cause tangible effects on the emission maxima.

First light-emitting electrochemical cell with [Ag(i)(N^N)(P^P)] type complex

A heteroleptic silver(i) complex has been prepared, characterized and selected for the first time as an active material for light-emitting electrochemical (LEC) devices. Its electronic properties, DFT and device performances have been systematically investigated.