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Two-Dimensional Antimony-Based Perovskite-Inspired Materials for High-Performance Self-Powered Photodetectors

The ongoing Internet of Things revolution has led to strong demand for low-cost, ubiquitous light sensing based on easy-to-fabricate, self-powered photodetectors. While solution-processable lead-halide perovskites have raised significant hopes in this regard, toxicity concerns have prompted the search for safer, lead-free perovskite-inspired materials (PIMs) with similar optoelectronic potential.

Lead-free cesium titanium bromide double perovskite nanocrystals

Double perovskites are a promising family of lead-free materials that not only replace lead but also enable new optoelectronic applications beyond photovoltaics. Recently, a titanium (Ti)-based vacancy-ordered double perovskite, Cs2 TiBr6, has been reported as an example of truly sustainable and earth-abundant perovskite with controversial results in terms of photoluminescence and environmental st

Primary photocatalytic water reduction and oxidation at an anatase TiO2 and Pt-TiO2 nanocrystalline electrode revealed by quantitative transient absorption studies

Quantitative assessments of electron and hole transfer dynamics with water on anatase nanocrystalline TiO2 films were conducted by employing a series of transient absorption spectrometers. For water reduction reactions, both conduction band and trapped electrons decay with two different single exponential components with the difference in time scale of 6∼7 orders of magnitudes. The faster reaction

Manganese Doping Promotes the Synthesis of Bismuth-based Perovskite Nanocrystals While Tuning Their Band Structures

The doping of halide perovskite nanocrystals (NCs) with manganese cations (Mn2+) has recently enabled enhanced stability, novel optical properties, and modulated charge carrier dynamics of the NCs host. However, the influence of Mn doping on the synthetic routes and the band structures of the host has not yet been elucidated. Herein, it is demonstrated that Mn doping promotes a facile, safe, and l

Tuning halide perovskite energy levels

The ability to control the energy levels in semiconductors is compelling for optoelectronic applications. In this study, we managed to tune the work function (WF) of halide perovskite semiconductors using self-assembled monolayers of small molecules to induce stable dipoles at the surface. The direction and intensity of the surface dipoles rely on specific molecule-to-surface interactions. Electro

N-substituted phenothiazines as environmentally friendly hole-transporting materials for low-cost and highly stable halide perovskite solar cells

Most of the high-performing halide perovskite solar cells (PSCs) leverage toxic chlorinated solvents (e.g., o-dichlorobenzene or chlorobenzene) for the hole-transporting material (HTM) processing and/or antisolvents in the perovskite film fabrication. To minimize the environmental and health-related hazards, it is highly desirable, yet at the same time demanding, to develop HTMs and perovskite dep

B-Site Co-Alloying with Germanium Improves the Efficiency and Stability of All-Inorganic Tin-Based Perovskite Nanocrystal Solar Cells

Colloidal lead-free perovskite nanocrystals have recently received extensive attention because of their facile synthesis, the outstanding size-tunable optoelectronic properties, and less or no toxicity in their commercial applications. Tin (Sn) has so far led to the most efficient lead-free solar cells, yet showing highly unstable characteristics in ambient conditions. Here, we propose the synthes

The Performance-Determining Role of Lewis Bases in Dye-Sensitized Solar Cells Employing Copper-Bisphenanthroline Redox Mediators

Copper redox mediators have enabled open-circuit voltages (VOC) of over 1.0 V in dye-sensitized solar cells (DSCs) and have helped to establish DSCs as the most promising solar cell technology in low-light conditions. The addition of additives such as 4-tert-butylpyridine (tBP) to these electrolytes has helped in achieving high solar cell performances. However, emerging evidence suggests that tBP

Synthesis of Insulated Heteroaromatic Platinum-Acetylide Complexes with Color-Tunable Phosphorescence in Solution and Solid States

Phosphorescence colors of cyclodextrin-based insulated Pt-acetylide complexes were tuned by the molecular engineering of the chromophores. A series of Pt complexes bearing various acetylide ligands, including heteroaromatics, were prepared via self-inclusion of the linked macrocycles with the complexes. The decline in the inclusion efficiency derived from the heteroaromatics was overcome by the la

Investigation of well-defined pinholes in TiO2 electron selective layers used in planar heterojunction perovskite solar cells

The recently introduced perovskite solar cell (PSC) technology is a promising candidate for providing low-cost energy for future demands. However, one major concern with the technology can be traced back to morphological defects in the electron selective layer (ESL), which deteriorates the solar cell performance. Pinholes in the ESL may lead to an increased surface recombination rate for holes, if

Complementary color tuning by HC1 via phosphorescence-to-fluorescence conversion on insulated metallopolymer film and its light-induced acceleration

An insulated metallopolymer that undergoes phosphorescence-to-fluorescence conversion between complementary colors by an acid-stimulus is proposed as a color-tunable material. A Pt-based phosphorescent metallopolymer, where the conjugated polymeric backbone is insulated by a cyclodextrin, is depolymerized by HCl via acidic cleavage of Pt-acetylide bonds to form a fluorescent monomer. The insulatio

Insulated conjugated bimetallopolymer with sigmoidal response by dual self-controlling system as a biomimetic material

Biological systems are known to spontaneously adjust the functioning of neurotransmitters, ion channels, and the immune system, being promoted or regulated through allosteric effects or inhibitors, affording non-linear responses to external stimuli. Here we report that an insulated conjugated bimetallopolymer, in which Ru(II) and Pt(II) complexes are mutually connected with insulated conjugations,

Advances in the stability of halide perovskite nanocrystals

Colloidal halide perovskite nanocrystals are promising candidates for next-generation optoelectronics because of their facile synthesis and their outstanding and size-tunable properties. However, these materials suffer fromrapid degradation, similarly to their bulk perovskite counterparts. Here, we survey the most recent strategies to boost perovskite nanocrystals stability, with a special focus o

Influence of hole mobility on charge separation and recombination dynamics at lead halide perovskite and spiro-ometad interface

High efficiency lead halide perovskite solar cells employ spiro-OMeTAD or PTAA as a hole transporting material. This type of hole conductor requires dopants mainly to improve hole mobility. Although such doping has improved solar cell performance, in particular open circuit photovoltage and fill factor, the mechanism of the improvement has rarely been elucidated. Here, we demonstrate influence of

Nanostructured TiO2 Grown by Low-Temperature Reactive Sputtering for Planar Perovskite Solar Cells

Low-temperature nanostructured electron-transporting layers (ETLs) for perovskite solar cells are grown by reactive sputtering at 160 °C with thickness in the range 22-76 nm and further stabilization in air at 180 °C to improve the lattice structure and to consequently reduce charge recombination during solar cell operation. In addition, the post-deposition treatment aims at leveling differences a

Thionation Enhances the Performance of Polymeric Dopant-Free Hole-Transporting Materials for Perovskite Solar Cells

To date, the most efficient perovskite solar cells (PSCs) require hole-transporting materials (HTMs) that are doped with hygroscopic additives to improve their performance. Unfortunately, such dopants negatively impact the overall PSCs stability and add cost and complexity to the device fabrication. Hence, there is a need to investigate new strategies to boost the typically modest performance of d

Liquid Crystallinity as a Self-Assembly Motif for High-Efficiency, Solution-Processed, Solid-State Singlet Fission Materials

Solution and solution-deposited thin films of the discotic liquid crystalline electron acceptor–donor–acceptor (A-D-A) p-type organic semiconductor FHBC(TDPP)2, synthesized by coupling thienyl substituted diketopyrrolopyrrole (TDPP) onto a fluorenyl substituted hexa-peri-hexabenzocoronene (FHBC) core, are examined by ultrafast and nanosecond transient absorption spectroscopy, and time-resolved pho

Halide Perovskite Nanocrystals for Next-Generation Optoelectronics

Colloidal perovskite nanocrystals (PNCs) combine the outstanding optoelectronic properties of bulk perovskites with strong quantum confinement effects at the nanoscale. Their facile and low-cost synthesis, together with superior photoluminescence quantum yields and exceptional optical versatility, make PNCs promising candidates for next-generation optoelectronics. However, this field is still in i

Identifying an Optimum Perovskite Solar Cell Structure by Kinetic Analysis : Planar, Mesoporous Based, or Extremely Thin Absorber Structure

Perovskite solar cells have rapidly been developed over the past several years. Choice of the most suitable solar cell structure is crucial to improve the performance further. Here, we attempt to determine an optimum cell structure for methylammonium lead iodide (MAPbI3) perovskite sandwiched by "2 and spiro-OMeTAD layers, among planar heterojunction, mesoporous structure, and extremely thin absor

Solution-Processable, Solid State Donor–Acceptor Materials for Singlet Fission

The exploitation of singlet fission (SF) materials in optoelectronic devices is restricted by the limited number of SF materials available and developing new organic materials that undergo singlet fission is a significant challenge. Using a new strategy based on conjugating strong donor and acceptor building blocks, the small molecule (BDT(DPP)2) and polymer (p-BDT-DPP) systems are designed and sy