Mechanochromic properties in a mononuclear Cu(I) complex without cuprophilic interactions.

Two polymorphs of Cu[(3,4-bis(diphenylphosphino)thiophene)(bis(pyrazol-1-yl)borohydrate)] (1) were isolated. The blue luminescent crystals have evident mechanochromic luminescent (MCL) properties. Based on photophysical and structural analysis, the pore structure in the blue crystals is considered to be the main reason for the MCL properties.

Self-Repairing Tin-Based Perovskite Solar Cells with a Breakthrough Efficiency Over 11.

The development of tin (Sn)-based perovskite solar cells (PSCs) is hindered by their lower power conversion efficiency and poorer stability compared to the lead-based ones, which arise from the easy oxidation of Sn2+ to Sn4+ . Herein, phenylhydrazine hydrochloride (PHCl) is introduced into FASnI3 (FA = NH2 CH  NH2 + ) perovskite films to reduce the existing Sn4+ and prevent the further degradation of FASnI3 , since PHCl has a reductive hydrazino group and a hydrophobic phenyl group. Consequently, the device achieves a record power conversion efficiency of 11.4% for lead-free PSCs. Besides, the unencapsulated device displays almost no efficiency reduction in a glove box over 110 days and shows efficiency recovery after being exposed to air, due to a proposed self-repairing trap state passivation process.

Dielectric Insights into the Microcosmic Behavior of Ionic Liquid-Based Self-Assembly-Microemulsions/Micelles.

Dielectric relaxation spectra of ([Bmim][BF4]/TX-100/ p-xylene) microemulsions and ([Bmim][BF4]/TX-100) micelles were measured. A specific dielectric relaxation changing with the concentration of ionic liquids (ILs) was observed in the range of 106-108 Hz. When dielectric parameters were combined with the Einstein displacement equation and Bruggeman's effective-medium approximation, the interaction between [Bmim][BF4] and p-(1,1,3,3-tetramethylbutyl) phenoxypolyoxyethyleneglycol (TX-100) in microemulsions/micelles was presented: because of the electrostatic interaction and van der Waals force, [Bmim][BF4] is bound around the polyethylene oxide (PEO) chains of TX-100, and once the electric field is added, ions of [Bmim][BF4] will move along the PEO chain. The dependence of dielectric and phase parameters such as relaxation time, permittivity, and volume fraction on the mass fraction of ILs presents an evidence for our proposals about the transition of both systems with the increase of IL content. In addition, it was confirmed that percolation is a unique phenomenon in microemulsions and the percolation mechanism here belongs to static percolation. The transition process of micelles with the change of IL content is presented from the dielectric view.

Mixed-Organic-Cation Tin Iodide for Lead-Free Perovskite Solar Cells with an Efficiency of 8.12.

In this work, a fully tin-based, mixed-organic-cation perovskite absorber (FA) x (MA)1-x SnI3 (FA = NH2CH = NH2+, MA = CH3NH3+) for lead-free perovskite solar cells (PSCs) with inverted structure is presented. By optimizing the ratio of FA and MA cations, a maximum power conversion efficiency of 8.12% is achieved for the (FA)0.75(MA)0.25SnI3-based device along with a high open-circuit voltage of 0.61 V, which originates from improved perovskite film morphology and inhibits recombination process in the device. The cation-mixing approach proves to be a facile method for the efficiency enhancement of tin-based PSCs.

A Breakthrough Efficiency of 19.9% Obtained in Inverted Perovskite Solar Cells by Using an Efficient Trap State Passivator Cu(thiourea)I.

It is extremely significant to study the trap state passivation and minimize the trap states of perovskite to achieve high-performance perovskite solar cells (PSCs). Here, we have first revealed and demonstrated that a novel p-type conductor Cu(thiourea)I [Cu(Tu)I] incorporated in perovskite layer can effectively passivate the trap states of perovskite via interacting with the under-coordinated metal cations and halide anions at the perovskite crystal surface. The trap state energy level of perovskite can be shallowed from 0.35-0.45 eV to 0.25-0.35 eV. In addition, the incorporated Cu(Tu)I can participate in constructing the p-i bulk heterojunctions with perovskite, leading to an increase of the depletion width from 126 to 265 nm, which is advantageous for accelerating hole transport and reducing charge carrier recombination. For these two synergistic effects, Cu(Tu)I can play a much better role than that of the traditional p-type conductor CuI, probably due to its identical valence band maximum with that of perovskite, which enables to not only lower the trap state energy level to a greater extent but also eliminate the potential wells for holes at the p-i heterojunctions. After optimization, a breakthrough efficiency of 19.9% has been obtained in the inverted PSCs with Cu(Tu)I as the trap state passivator of perovskite.

A Strategy to Simplify the Preparation Process of Perovskite Solar Cells by Co-deposition of a Hole-Conductor and a Perovskite Layer.

The feasibility of co-depositing a hole-conductor and a perovskite layer is demonstrated to simplify the preparation process of perovskite solar cells. The CuSCN incorporated in the perovskite layer can participate in forming the perovskite/CuSCN bulk-heterojunction and accelerate hole transport effectively, which eventually leads to a maximum power conversion efficiency of 18.1% with almost no J-V hysteresis.

High-performance inverted planar heterojunction perovskite solar cells based on a solution-processed CuOx hole transport layer.

During the past several years, methylammonium lead halide perovskites have been widely investigated as light absorbers for thin-film photovoltaic cells. Among the various device architectures, the inverted planar heterojunction perovskite solar cells have attracted special attention for their relatively simple fabrication and high efficiencies. Although promising efficiencies have been obtained in the inverted planar geometry based on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) sulfonic acid ( PEDOT: PSS) as the hole transport material (HTM), the hydrophilicity of the PEDOT: PSS is a critical factor for long-term stability. In this paper, a CuOx hole transport layer from a facile solution-processed method was introduced into the inverted planar heterojunction perovskite solar cells. After the optimization of the devices, a champion PCE of 17.1% was obtained with an open circuit voltage (Voc) of 0.99 V, a short-circuit current (Jsc) of 23.2 mA cm(-2) and a fill factor (FF) of 74.4%. Furthermore, the unencapsulated device cooperating with the CuOx film exhibited superior performance in the stability test, compared to the device involving the PEDOT: PSS layer, indicating that CuOx could be a promising HTM for replacing PEDOT: PSS in inverted planar heterojunction perovskite solar cells.

Solution-Processed CuS NPs as an Inorganic Hole-Selective Contact Material for Inverted Planar Perovskite Solar Cells.

Organic-inorganic hybrid perovskite solar cells (PSCs) have drawn worldwide intense research in recent years. Herein, we have first applied another p-type inorganic hole-selective contact material, CuS nanoparticles (CuS NPs), in an inverted planar heterojunction (PHJ) perovskite solar cell. The CuS NP-modification of indium tin oxide (ITO) has successfully tuned the surface work function from 4.9 to 5.1 eV but not affect the surface roughness and transmittance, which can effectively reduce the interfacial carrier injection barrier and facilitate high hole extraction efficiency between the perovskite and ITO layers. After optimization, the maximum power conversion efficiency (PCE) has been over 16% with low J-V hysteresis and excellent stability. Therefore, the low-cost solution-processed and stable CuS NPs would be an alternative interfacial modification material for industrial production in perovskite solar cells.