Bottom-up design of functional device components based on nanometer-sized building blocks relies on accurate control of their self-assembly behavior. Atom-precise metal nanoclusters are well-characterizable building blocks for designing tunable nanomaterials, but it has been challenging to achieve directed assembly to macroscopic functional cluster-based materials with highly anisotropic properties. Here, we discover a solvent-mediated assembly of 34atom intermetallic gold-silver clusters protected by 20 1-ethynyladamantanes into 1D polymers with Ag-Au-Ag bonds between neighboring clusters as shown directly by the atomic structure from single-crystal X-ray diffraction analysis. Density functional theory calculations predict that the single crystals of cluster polymers have a band gap of about 1.3 eV. Fieldeffect transistors fabricated with single crystals of cluster polymers feature highly anisotropic p-type semiconductor properties with ≈1800-fold conductivity in the direction of the polymer as compared to cross directions, hole mobility of ≈0.02 cm 2 V −1 s −1 , and an ON/OFF ratio up to ≈4000. This performance holds promise for further design of functional cluster-based materials with highly anisotropic semiconducting properties.
Crown ether effectively stabilizes the cubic phase of CsPbI3 to inhibit the moisture invasion and phase transformation of CsPbI3 films, producing large-area devices and improving device performance.
Perovskite
films prepared with CH3NH2 molecules
under ambient conditions have led to rapid fabrication of perovskite
solar cells (PSCs), but there remains a lack of mechanistic studies
and inconsistencies with operability in their production. Here the
crystal structure of CH3NH2–CH3NH3PbI3 was analyzed to involve hydrogen bonds
(CH3NH2···CH3NH3
+) and has guided the facile, reproducible preparation
of high-quality perovskite films under ambient conditions. Hydrogen
bonds within CH3NH2···CH3NH3
+ dimers were found in the CH3NH2–CH3NH3PbI3 intermediates, accompanied by 1D-PbI3
– chains (δ-phase). The weakly hydrogen-bonded CH3NH2 molecules were easily released from the CH3NH2–CH3NH3PbI3 intermediates, contributing to rapid, spontaneous phase transition
from 1D-PbI3
– (δ-phase) to 3D-PbI3
– (α-phase). Further introduction
of CH3NH3Cl into the CH3NH2–CH3NH3PbI3 intermediates
led to interruption of 1D-PbI3
– transition
into 0D-Pb2I9‑x
Cl
x
5–(0 < x < 6), adjusting the phase transition route toward 3D-PbI3
–. On the basis of the above understanding,
CH3NH2 solution in ethanol and CH3NH3Cl were used for precursors and a best efficiency of
20.3% in PSCs was achieved. Large-scale modules (12 cm2 aperture area) fabricated by a dip-coating technology exhibited
an efficiency up to 16.0% and outstanding stability over 10 000
s under continuous output. The developed preparation method of perovskite
precursors and insightful research into the methylamine-dimer-induced
phase transition mechanism have enabled the production of high-quality
perovskite films with robust operability, showing great potential
for large-scale commercialization.
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