Large-Grained All-Inorganic Bismuth-Based Perovskites with Narrow Band Gap via Lewis Acid–Base Adduct Approach

Abstract

Bismuth halide perovskites have recently been considered a potential alternative to lead halide analogues due to their low toxicity and high stability. However, the layered flake structure and wide band gap limit their applications in perovskite solar cells (PSCs). We herein show that large-grained allinorganic bismuth-based perovskites with a narrow band gap can be obtained from a Lewis acid−base adduct reaction under ambient conditions. Thiourea (CH 4 N 2 S) is utilized as a Lewis base to interact with BiI 3 , confirmed with infrared (IR) spectra. The strong coordination between thiourea and the Bi 3+ center could slow down the perovskite crystallization and promote the preferred orientation of the perovskite crystals with a hexagonal phase. The morphology of the perovskite films varies dramatically with an increase of molar ratio of BiI 3 and thiourea in the precursor. The perovskites derived from a BiI 3 /thiourea ratio of 1:2 display extrathick grains, higher surface coverage, extended light absorption, higher crystallinity, and similar air stability compared to the pristine sample. The power conversion efficiency (PCE) of the thioureainduced bismuth perovskite solar cells is significantly enhanced due to the higher surface coverage and the broader absorption of the perovskite film.

Exceptional High and Reversible Ammonia Uptake by Two Dimension Few-layer BiI3 Nanosheets

“…For instance, the yield and dispersion concentration of exfoliated BiI 3 nanosheets in triacetin-EDTAD solutions were 4.5 times that in neat triacetin, respectively. On the other hand, the stripping efficiency of BiI 3 nanosheets in triacetin-salt solutions decreased in the order: EDTAD > SDTT > SDCT, which was roughly agreement with the order for Lewis basic strength of anion in the salts. − This order suggests that the strong Lewis acid–base interaction between Bi cation (as Lewis acid) and anion of the salts (as Lewis base) plays a significant part in the exfoliation of BiI 3 nanosheets …”

“…29−31 This order suggests that the strong Lewis acid−base interaction between Bi cation (as Lewis acid) and anion of the salts (as Lewis base) plays a significant part in the exfoliation of BiI 3 nanosheets. 32 Figure 1a−d and SI Figures S4 and S5 show the scanning electron microscopy (SEM) and transmission electron microscopy (TEM) mages of the bulk BiI 3 and BiI 3 nanosheets. Taking BiI 3 nanosheets prepared in SDCTtriacetin solution as an example, BiI 3 nanosheets have smaller size and a thin, transparent and overlapping planar structure compared with the unexfoliated BiI 3 .…”

Alloying Sb into all inorganic lead-free CsBi3I10 for improving the crystal growth and photovoltaic performance

“…On the other hand, ion substitution by incorporating appropriate ions into the host lattices has been proven to be an effective strategy to tailor the optoelectronic properties (such as bandgaps, trap states, and charge transport) of various perovskite materials. [27][28][29][30][31][32][33][34][38][39][40][41] For example, Kanatzidis's group alloyed the Sn 2+ into MAPbI 3 , achieving a narrowed bandgap of <1.3 eV and extending the photoresponse to the infrared region (up to 1050 nm) for the solid solution of MASn 1Àx Pb x I 3 . 35 Notably, the suitable ion substitution can also improve the lm morphology of perovskites.…”

“…This rapid crystallization phenomenon for Bi-based perovskites is likely due to the much lower solubility of BiI 3 precursor and its weaker coordinating strength with the common Lewis base solvents. 38,39 The surface scanning electron microscope (SEM) image (Fig. 1b) indicates that the pristine CBI lm is mostly consisted of randomly-oriented ultrasmall nanoparticles, due to the fast solvent evaporation during thermal annealing.…”

Self-Assembled Organic Cations-Assisted Band-Edge Tailoring in Bismuth-Based Perovskites for Enhanced Visible Light Absorption and Photoconductivity

“…In contrast, the excitons generated in BPBI are strongly confined in the isolated BiI 6 3– octahedrons and subsequently resulted in a weak TRMC signal. There are several reports of using zero-dimensional bismuth halide perovskites as a light-absorbing layer in photovoltaic devices. ,, Our materials may also be suitable for such devices, particularly NDBI, which has a relatively low bandgap. Further, these materials may be employed as a top cell light absorber in tandem solar cells consisting of c-Si or CIGS as the bottom cells to improve the overall efficiencies.…”