2D BA2PbI4 Regulating PbI2 Crystallization to Induce Perovskite Growth for Efficient Solar Cells.

Using seeds to control the crystallization of perovskite film is an effective strategy for achieving high-efficiency perovskite solar cells (PSCs). Owing to their excellent environmental stability brought by their long alkyl chain, n-butylammonium (BA) cations are widely used for fabricating efficient and stable PSCs. However, BA-based 2D perovskite is seldom been investigated as a seed. Here, BA2PbI4 is employed to regulate the crystallization of PbI2, acting as nucleation centers. As a result, porous PbI2 film with high crystallinity is obtained, which allows the realization of perovskite film with preferential crystal orientations of (001) and large grain size of over 2 µm. The corresponding PSC achieves a high power conversion efficiency (PCE) of 24.30% and exhibits satisfactory stability, retaining 91.70% of the initial PCE after 300 h of thermal aging at 85°C.

Dual-Interface Engineering in Perovskite Solar Cells with 2D Carbides.

Passivating the interfaces between the perovskite and charge transport layers is crucial for enhancing the power conversion efficiency (PCE) and stability in perovskite solar cells (PSCs). Here we report a dual-interface engineering approach to improving the performance of FA0.85 MA0.15 Pb(I0.95 Br0.05 )3 -based PSCs by incorporating Ti3 C2 Clx Nano-MXene and o-TB-GDY nanographdiyne (NanoGDY) into the electron transport layer (ETL)/perovskite and perovskite/ hole transport layer (HTL) interfaces, respectively. The dual-interface passivation simultaneously suppresses non-radiative recombination and promotes carrier extraction by forming the Pb-Cl chemical bond and strong coordination of π-electron conjugation with undercoordinated Pb defects. The resulting perovskite film has an ultralong carrier lifetime exceeding 10 µs and an enlarged crystal size exceeding 2.5 µm. A maximum PCE of 24.86 % is realized, with an open-circuit voltage of 1.20 V. Unencapsulated cells retain 92 % of their initial efficiency after 1464 hours in ambient air and 80 % after 1002 hours of thermal stability test at 85 °C.

Graphdiyne and Its Derivatives as Efficient Charge Reservoirs and Transporters in Semiconductor Devices.

2D graphdiyne (GDY), which is composed of sp and sp2 hybridized carbon atoms, is a promising semiconductor material with a unique porous lamellar structure. It has high carrier mobility, tunable bandgap, high density of states, and strong electrostatic interaction ability with ions and organic functional units. In recent years, interests in applying GDYs (GDY and its derivatives) in semiconductor devices have been growing rapidly, and great achievements have been made. Attractively, GDYs could act as efficient reservoirs and transporters for both carriers and ions, which endows them with enormous potential in future novel optoelectronics. In this review, the progress in this field is systematically summarized, aiming to bring an in-depth insight into the GDYs' intrinsic uniqueness. Particularly, the effects of GDYs on carrier dynamics and ionic interactions in various semiconductor devices are succinctly described, analyzed, and concluded.

Dual Core-Shell-Structured S@C@MnO2 Nanocomposite for Highly Stable Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries have currently excited worldwide academic and industrial interest as a next-generation high-power energy storage system (EES) because of their high energy density and low cost of sulfur. However, the commercialization application is being hindered by capacity decay, mainly attributed to the polysulfide shuttle and poor conductivity of sulfur. Here, we have designed a novel dual core-shell nanostructure of S@C@MnO2 nanosphere hybrid as the sulfur host. The S@C@MnO2 nanosphere is successfully prepared using mesoporous carbon hollow spheres (MCHS) as the template and then in situ MnO2 growth on the surface of MCHS. In comparison with polar bare sulfur hosts materials, the as-prepared robust S@C@MnO2 composite cathode delivers significantly improved electrochemical performances in terms of high specific capacity (1345 mAh g-1 at 0.1 C), remarkable rate capability (465 mA h g-1 at 5.0 C) and excellent cycling stability (capacity decay rate of 0.052% per cycle after 1000 cycles at 3.0 C). Such a structure as cathode in Li-S batteries can not only store sulfur via inner mesoporous carbon layer and outer MnO2 shell, which physically/chemically confine the polysulfides shuttle effect, but also ensure overall good electrical conductivity. Therefore, these synergistic effects are achieved by unique structural characteristics of S@C@MnO2 nanospheres.