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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

Excitation wavelength dependent interfacial charge transfer dynamics in a CH3NH3PbI3 perovskite film

Elucidation of interfacial charge separation and recombination mechanisms is crucial to improve performance of organic-inorganic metal halide perovskite solar cells. Here, we have investigated influence of initially populated electron and hole potential levels in a perovskite conduction band (CB) and valence band (VB), respectively, by altering an excitation wavelength on interfacial charge separa

Wafer-Scale Synthesis of Semiconducting SnO Monolayers from Interfacial Oxide Layers of Metallic Liquid Tin

Atomically thin semiconductors are one of the fastest growing categories in materials science due to their promise to enable high-performance electronic and optical devices. Furthermore, a host of intriguing phenomena have been reported to occur when a semiconductor is confined within two dimensions. However, the synthesis of large area atomically thin materials remains as a significant technologi

Fluorene-Thiophene Copolymer Wire on TiO2 : Mechanism Achieving Long Charge Separated State Lifetimes

Insertion of interfacial molecules in bulk heterojunction and dye sensitized solar cells is effective to retard charge recombination reactions and thus to improve solar cell performance. So far, to extend charge separated state lifetime, the molecule was designed to increase distance between an n-type and a p-type semiconductors to reduce their electronic coupling. Here we investigated a series of

Light intensity dependence of performance of lead halide perovskite solar cells

Performance of nanoporous TiO2 based lead iodide perovskite solar cells was investigated under a series of light intensity up to 1.2 sun. The short circuit photocurrent increases linearly with the intensity increase, while the fill factor slightly decreases with the intensity increase. The analysis of logarithmic light intensity dependence of the open circuit voltage revealed a slope of 1.09 kT/q,

Hetero Face-to-Face Porphyrin Array with Cooperative Effects of Coordination and Host–Guest Complexation

We successfully synthesized a hetero face-to-face porphyrin array composed of ZnTPP and RuTPP(DABCO)2 (TPP: 5, 10, 15, 20-tetraphenylporphyrin, DABCO: 1,4-diazabi-cyclo[2.2.2]octane) in 2:1 molar ratio. A cyclic Zn porphyrin dimer (ZnCP) was also used as the host molecule for the Ru porphyrin. In the latter, the Ru-DABCO bonding in RuTPP(DABCO)2 was stabilized by the host-guest complexation. React

Monodisperse and size-tunable PbS colloidal quantum dots via heterogeneous precursors

PbS quantum dots (QDs) are some of the most attractive QDs used to develop novel optoelectronic devices such as solar cells, photodetectors and biological labels. However, identifying an appropriate method to access high quality QDs with a wide size range employing lower cost, less toxic and safer precursors is not trivial. Here, we demonstrate the diffusion controlled synthesis of size-tunable Pb

Stable eye versus mouth preference in a live speech-processing task

Looking at the mouth region is thought to be a useful strategy for speech-perception tasks. The tendency to look at the eyes versus the mouth of another person during speech processing has thus far mainly been studied using screen-based paradigms. In this study, we estimated the eye-mouth-index (EMI) of 38 adult participants in a live setting. Participants were seated across the table from an expe

The Database of European Forest Insect and Disease Disturbances: DEFID2

Insect and disease outbreaks in forests are biotic disturbances that can profoundly alter ecosystem dynamics. In many parts of the world, these disturbance regimes are intensifying as the climate changes and shifts the distribution of species and biomes. As a result, key forest ecosystem services, such as carbon sequestration, regulation of water flows, wood production, protection of soils, and th

Family display and recognition in bonus relations

Bonus relations (such as step-grandparents, step-grandchildren, and families of choice) can be chosen, or they can be forced up on you, they can be regarded as very important to extremely peripheral. Bonus relations negotiate familiarity and can vary from inclusion to exclusion. Common to bonus-relations are their non-biological aspect: they are not blood-line relations, and to many families and fBonus relations (such as step-grandparents, step-grandchildren, and families of choice) can be chosen, or they can be forced up on you, they can be regarded as very important to extremely peripheral. Bonus relations negotiate familiarity and can vary from inclusion to exclusion. Common to bonus-relations are their non-biological aspect: they are not blood-line relations, and to many families and f