Enhanced Charge Injection and Recombination of CsPbBr₃ Perovskite Nanocrystals upon Internal Heterovalent Substitution

Abstract

Heterovalent substitution of the Pb(II) cation of CsPbBr 3 perovskite nanocrystals (PNCs) with Sb(III) cation is developed as an internal engineering strategy to tailor their optoelectrical properties. Partially replacing Pb(II)−Br bonds of cubic CsPbBr 3 PNCs with stronger Sb(III)−Br bonds can not only enlarge the band gap and preserve the highly-passivated surface states of parent PNCs but also enable the obtained Sb(III)−CsPbBr 3 PNCs with both blue-shifted and enhanced absorbance, photoluminescence, and electrochemiluminescence as well as boosted electron and hole-injection responses via electrochemical redox. The enhanced absorbance and radiative charge transfer originate from both the increased vacancies in crystals and the impurity states in the band gap of PNCs upon substituting Pb(II) with Sb(III) because the increased vacancies are more favorable to recombine the electrons injected via photoexcitation and/or electrochemical redox, while suitable impurity states in the band gap of PNCs also facilitate electron transfer for charge recombination. Sb(III)−CsPbBr 3 PNCs are promising monochromatic fluorophores and electrochemiluminophores; therefore, judiciously choosing suitable internal-engineering strategy to process PNCs has promise for their extended application.

Enhanced Photoluminescence Quantum Yield, Lifetime, and Photodetector Responsivity of CsPbBr3 Quantum Dots via Antimony Tribromide Post-Treatment

“…After aging for a couple of hours, Sb 3+ diffused slowly into the CsPbBr 3 QD lattice and influenced the optical properties and PLQY enhancement. Doping of smaller-ionic-radius Sb 3+ could increase the cohesive energy and tolerance factor of the CsPbBr 3 QD crystal structure, which mainly induce the stability of the QDs. , …”

“…Doping of smaller-ionic-radius Sb 3+ could increase the cohesive energy and tolerance factor of the CsPbBr 3 QD crystal structure, which mainly induce the stability of the QDs. 32,33 As-synthesized and post-treated CsPbBr 3 QD elemental compositions were analyzed using XPS characterization. The survey scan of as-synthesized and post-treated QD spectra illustrates the presence of Cs 3d, Pb 4f, and Br 3d, as shown in Figures S6 and S7, respectively.…”

“…They observed that the replacement of the Pb(II)−Br bond with a strong Sb(III)−Br bond can preserve the highly passivated surface states of as-synthesized CsPbBr 3 QDs and improve the optoelectronic properties of CsPbBr 3 QDs. 32 Similarly, Bera et al fabricated efficient Sb 3+ -doped CsPbI 3 QD solar cells with enhanced stability compared to the undoped QDs. The stability of the device improved effectively after substitution of the smaller-radius Sb 3+ (76 pm) cation with the larger-radius Pb 2+ (119 pm) cation with an improved tolerance factor.…”

“…synthesized heterovalent ions with the Sb 3+ cation substituted in CsPbBr 3 QDs. They observed that the replacement of the Pb­(II)–Br bond with a strong Sb­(III)–Br bond can preserve the highly passivated surface states of as-synthesized CsPbBr 3 QDs and improve the optoelectronic properties of CsPbBr 3 QDs . Similarly, Bera et al fabricated efficient Sb 3+ -doped CsPbI 3 QD solar cells with enhanced stability compared to the undoped QDs.…”

Recent Progress in Electrochemiluminescence of Halide Perovskites

“…Heterovalent substitution is also proposed to tailor the optoelectrical attributes of PeNCs. Jia et al (2019) directly introduced Sb 3+ (Sb/Pb = 1:3, molar ratio) in the synthesizing procedure of CsPbBr 3 NCs via HIR. The partial replaces of Pb 2+ −Br bonds with strong Sb 3+ −Br bonds enlarged the band gap and preserved highly passivated surface states.…”