penghuang

A new hole-transport material (HTM) based on the 1,3,4-oxadiazole moiety (H1) was prepared through a single-step synthetic pathway starting from commercially available products. Thanks to a deep HOMO level, H1 was used as HTM in CH₃NH₃PbBr₃ perovskite solar cells yielding an efficiency of 5.8 %. The reference HTM (Spiro-OMeTAD), under the same testing conditions, furnished a lower efficiency of 5.1 %. Steady-state and time-resolved photoluminescence of the thin films showed good charge-extraction dynamics for H1 devices. In addition, H1 shows a large thermal stability and completely amorphous behavior (as evaluated by thermal gravimetric analysis and differential scanning calorimetry).

Efficiency on sale: An oxadiazole-based π-spacer is used in a new donor–π–donor structured hole-transport material for perovskite solar cells. When tested in a device, this compound yields power conversion efficiency values higher than the commonly used reference material. Thanks to the extremely simple synthetic route, this material helps to achieve an important goal in the field of perovskite solar cells: fabrication of high performance devices, while reducing costs.

The photocatalytic hydrogen evolution activities of low-cost and noble-metal-free Cu₂XSnS₄ (X=Zn, Ni, Fe, Co, and Mn) nanofiber catalysts have been investigated using triethanolamine as an electron donor and eosin Y as a photosensitizer under visible-light irradiation. The rates of hydrogen evolution by Cu₂XSnS₄ (X=Zn, Ni, Fe, Co, and Mn) nanofibers have been compared with each other and with that of the noble metal Pt. The hydrogen evolution rates for the nanofibers change in the order Cu₂NiSnS₄>Cu₂FeSnS₄>Cu₂CoSnS₄>Cu₂ZnSnS₄>Cu₂MnSnS₄ (2028, 1870, 1926, 1420, and 389 μmol g⁻¹ h⁻¹, respectively). The differences between the hydrogen evolution rates of the nanofibers could be attributed to their energy levels. Moreover, Cu₂NiSnS₄, Cu₂FeSnS₄, and Cu₂CoSnS₄ nanofibers show higher and more stable photocatalytic hydrogen production rates than that of the noble metal Pt under long-term irradiation with visible light.

High-fiber catalysts: Low-cost and noble-metal-free Cu₂XSnS₄ (X=Zn, Ni, Fe, Co and Mn) nanofibers are prepared by an electrospinning process and used for photocatalytic hydrogen evolution from water through dye sensitization.

CdS nanowires decorated with ultrathin MoS₂ nanosheets were synthesized for the first time by ultrasonic exfoliation by using dimethylformamide as the dispersing agent. An excellent hydrogen evolution rate of 1914 μmol h⁻¹ (20 mg catalyst) under visible-light irradiation (λ≥400 nm, ≈154 mW cm⁻¹) and an apparent quantum yield of 46.9 % at λ=420 nm were achieved over the MoS₂/CdS composite. The presence of ultrathin MoS₂ nanosheets (rich in active edge sites) on the CdS surface promotes the separation of photogenerated charge carriers and facilitates the surface processes of photocatalytic hydrogen evolution.

Down to the wire: A composite comprising CdS nanowires decorated with ultrathin MoS₂ nanosheets is synthesized by an ultrasonic exfoliation method using dimethylformamide as a dispersing agent. The composite shows high photocatalytic efficiency for hydrogen evolution.

We developed a new donor–π–acceptor-type hole-transport material (HTMs) incorporating S,N-heteropentacene as π-spacer, triarylamine as donor, and dicyanovinylene as acceptor. In addition to appropriate frontier molecular orbital energies, the new HTM showed high photo absorptivity in the visible region. Without the use of p-dopants, solution-processed mixed perovskite devices using the HTM achieved power conversion efficiencies of up to 16.9% and high photocurrents of up to 22.2 mA cm⁻². These results demonstrate that heteroacene can be an excellent building block to prepare alternative HTMs for perovskite solar cells and hold promise for further advancement through fine-tuning the molecular structure.

Alternative transport: A novel hole-transport material based on S,N-heteropentacene is reported for perovskite solar cells, exhibiting excellent power conversion efficiency of 16.9 % in the absence of p-type dopants. This represents a significant advancement in the field of alternative hole-transport materials for perovskite solar cells.

A highly efficient Cu₂ZnSn(S,Se)₄ (CZTSSe)-based thin-film solar cell (9.9 %) was prepared using an electrochemical deposition method followed by thermal annealing. The Cu–Zn–Sn alloy films was grown on a Mo-coated glass substrate using a one-pot electrochemical deposition process, and the metallic precursor films was annealed under a mixed atmosphere of S and Se to form CZTSSe thin films with bandgap energies ranging from 1.0 to 1.2 eV. The compositional modification of the S/(S+Se) ratio shows a trade-off effect between the photocurrent and photovoltage, resulting in an optimum bandgap of roughly 1.14 eV. In addition, the increased S content near the p–n junction reduces the dark current and interface recombination, resulting in a further enhancement of the open-circuit voltage. As a result of the compositional and interfacial modification, the best CZTSSe-based thin-film solar cell exhibits a conversion efficiency of 9.9 %, which is among the highest efficiencies reported so far for electrochemically deposited CZTSSe-based thin-film solar cells.

Thin films modified: A highly efficient Cu₂ZnSn(S,Se)₄ (CZTSSe)-based thin-film solar cell is prepared using an electrochemical deposition method followed by thermal annealing. As a result of the compositional and interfacial modification of the CZTSSe thin film, the conversion efficiency can be increased up to 9.9 %, which is the highest efficiency among the CZTSSe-based thin-film solar cells prepared through electrochemical deposition.

Realizing the continuous and large scale preparation of particle/carbon nanotube (CNT) composites with enhanced functionalities, and broad applications in energy conversion, harvesting, and storage systems, remains as a big challenge. Here, we report a scalable strategy to continuously prepare particle/CNT composite films in which particles are confined by CNT films. This is achieved by the continuous condensation and deposition of a cylindrical assembly of CNTs on a paper strip and the in situ incorporation of particles during the layer-by-layer deposition process. A Cu/CNT composite film is prepared as an example; such a film exhibits very high power conversion efficiency when it is used as a counter electrode in a solar cell, compared with previous materials under otherwise identical conditions. The proposed method can be extended to other CNT-based composite films with excellent functionalities for wide applications.

Easy electrode: A general strategy is developed to continuously prepare particle/carbon nanotube (CNT) composite films. A Cu/CNT composite film is demonstrated as an example. Such film exhibits excellent performance when used as a counter electrode in a quantum-dot-sensitized solar cells compared with commonly used Pt and CNT electrodes.

A new class of hole-transport materials (HTMs) based on the bimesitylene core designed for mesoporous perovskite solar cells is introduced. Devices fabricated using two of these derivatives yield higher open-circuit voltage values than the commonly used spiro-OMeTAD. Power conversion efficiency (PCE) values of up to 12.11 % are obtained in perovskite-based devices using these new HTMs. The stability of the device made using the highest performing HTM (P1) is improved compared with spiro-OMeTAD as evidenced through long-term stability tests over 1000 h.

Stability trumps efficiency: Three hole-transport materials based on a bimesitylene core presented, and their application in perovskite solar cells is evaluated. An overall power conversion efficiency of up to 12.11 % is achieved with these new materials and stability studies show that the long-term stability of devices using the new materials is superior to commonly used spiro-OMeTAD.