Enhanced and Tunable Emission from Organic–Inorganic Metal Halide Perovskites A2ZrCl6:Sb3+ via A-Site Organic Cation Manipulation

The substitution of an inorganic cation (such as Cs⁺) by an organic group has provided a great opportunity for enhancing and enriching the emission from metal halide perovskites because of the abundant changes in the organic molecule. However, the emission modulation by changing the organic group has been rarely reported. Herein, Cs⁺ in Cs₂ZrCl₆:Sb³⁺ was substituted by a series of organic groups. The substitution by butyltriphenylphosphonium (BTP) generated a monoclinic crystal with a P2₁/n space group, which was determined by single-crystal diffraction. (BTP)₂ZrCl₆:Sb³⁺ features typical dual-band emissions from self-trapped excitons. Moreover, because of the large distance (>11 Å) among the [ZrCl₆]^2- octahedra, more Sb³⁺ dopants can be tolerated before concentration quenching. Consequently, (BTP)₂ZrCl₆:Sb³⁺ exhibited high inner and external quantum efficiencies of 96.2 and 73.5%, respectively. Furthermore, the butyl group of BTP was changed to other groups with different sizes and electronic states. The small change of the organic group can effectively tailor the emission intensity (I_maximum/I_minimum = 7.06 ± 0.08) and wavelength (615-665 nm). The applications of (BTP)₂ZrCl₆:Sb³⁺ in white light-emitting diodes (WLEDs) and anticounterfeiting were demonstrated. Our work not only presents well-performed organic-inorganic metal halide perovskites but also indicates the need for an elaborate design of the organic cations.