Perovskite‐Derivative Valleytronics

Abstract

Halide perovskites are revolutionizing the renewable energy sector owing to their high photovoltaic efficiency, low manufacturing cost, and flexibility. Their remarkable mobility and long carrier lifetime are also valuable for information technology, but fundamental challenges like poor stability under an electric field prevent realistic applications of halide perovskites in electronics. Here, it is discovered that valleytronics is a promising route to leverage the advantages of halide perovskites and derivatives for information storage and processing. The synthesized all‐inorganic lead‐free perovskite derivative, Cs3Bi2I9, exhibits strong light–matter interaction and parity‐dependent optically addressable valley degree of freedom. Robust optical helicity in all odd‐layer‐number crystals with inversion symmetry breaking is observed, indicating excitonic coherence extending well beyond 11 layers. The excellent optical and valley properties of Cs3Bi2I9 arise from the unique parallel bands, according to first principles calculations. This discovery points to new materials design principles for scalable valleytronic devices and demonstrates the promise of perovskite derivatives beyond energy applications.

Promoted photocarrier separation by dipole engineering in two-dimensional perovskite/C2N van der Waals heterostructures

“…The two aromatic rings are joined together by pyrazine rings that are made up of a six-membered D 2h point group with two N atoms facing each other. 41 The optimized lattice constants of the unit cell are 8.60 Å and 8.33 Å for the individual Cs 3 Bi 2 I 9 and C 2 N, respectively, which are consistent with the previously reported results, 40,69 confirming the reliability of the following calculated results. The analogous lattice constants of Cs 3 Bi 2 I 9 and C 2 N suggest the likelihood of epitaxial stacking, especially in few-layer systems.…”

“…These values are in good agreement with the previous theoretical calculations. 29,44,50,69 Moreover, in Fig. 1(e) and (f), the calculated total density of states (TDOS) and the projected density of states (PDOS) show that the CBM of the Cs 3 Bi 2 I 9 comprises I-5p and Bi-6p states, while the VBM is only dominated by I-5p states.…”

“…These values are in good agreement with the previous theoretical calculations. 29,44,50,69 Moreover, in Fig. 1 2(a) is built by attaching the unit cells of each component together with a total atom number of 32.…”

Dimension-Dependent Bandgap Narrowing and Metallization in Lead-Free Halide Perovskite Cs3Bi2X9 (X = I, Br, and Cl) under High Pressure

“…Recently, nontoxic, all-inorganic, lead-free Bi-based perovskites have attracted significant attention owing to their stability, high photoluminescence, high quantum yield, and tunable bandgaps [11][12][13][14][15][16][17]. They have been widely used in applications, such as memory devices, photodetectors, solar cells, and X-ray detectors [18][19][20][21][22][23][24][25][26]. However, many studies have shown that there are some challenges to overcome for the use of Cs 3 Bi 2 X 9 (X = I, Br, and Cl) perovskites in photovoltaic devices.…”

Latest applications of ToF-SIMS characterization for next-generation electronic materials

“…Finally, we will finish by demonstrating how the retrospective analysis using ToF-SIMS can be very powerful and useful for exploring any single feature in 2D materials [3,4]. Typically, ToF-SIMS acquisition is recording a full mass range spectrum per pixel (or voxel), which permits to isolate and to decorrelate specific regions of interest for resolving interfaces, diffusion, and doping in thin 2D structures.…”