Photoluminescence Behavior of Zero-Dimensional Manganese Halide Tetrahedra Embedded in Conjugated Organic Matrices

Abstract

Zero-dimensional hybrid manganese halides with the type-I band alignment between the manganese halide tetrahedra and organic matrices have attracted much attention as highly efficient narrow-band green emitters. Herein we study the photoluminescence (PL) behavior of hybrid manganese bromides with type-II band alignment, where the lowest unoccupied molecular orbital (LUMO) level can be tuned by employing quaternary phosphonium dications with different degrees of conjugation. For low-conjugated organic matrices, the band alignment can shift from type II in the ground state to type I in the excited state, which enables high photoluminescence quantum yields. In contrast, for high-conjugated organic matrices, the band alignment cannot convert to type I in the excited state because the LUMO lies too low, and thus, the excited electrons are transferred from the tetrahedra to the matrices, which leads to severe PL quenching. Our results show the importance of the excited-state band alignment for understanding the PL behavior of hybrid metal halide semiconductors.

Integrated Afterglow and Self‐Trapped Exciton Emissions in Hybrid Metal Halides for Anti‐Counterfeiting Applications

“…The ultrafast energy transfer occurs from the S 1 state in Ph 3 S + to the STE state of [TeCl 6 ] 2− units, thus the excitons are confined in [TeCl 6 ] 2− octahedral units. [ 7a,19 ] Therefore, most excitons relax from STE state to S 0 to yield STE emission. The coexistence of [SnCl 6 ] 2− and [TeCl 6 ] 2− units in Sn–Te–Cl leads to the exciton relaxation not only from STE state to S 0 but also from ET 3 to the triplet states of Ph 3 S + .…”

Enhanced Photoluminescence of All-Inorganic Manganese Halide Perovskite-Analogue Nanocrystals by Lead Ion Incorporation

“…Mn 2+ is a commonly used dopant for altering magnetic, electrical and optical properties of materials. − Introduction of Mn 2+ into perovskite host lattice significantly increases the stability and luminescence performance of the crystal structure. − Due to the advantages of low toxicity and high abundance of Mn as well as the Mn 2+ d–d transition with emission featuring a large Stokes shift and long excited state lifetime, Mn 2+ has been considered as an efficient light emission center in metal halide perovskites . Replacing Pb 2+ with Mn 2+ to obtain Mn-based perovskites, including organic–inorganic hybrid and all-inorganic manganese-based perovskites, has been studied in recent years. ,− For Mn-based perovskites, the absorption and emission of Mn 2+ are strongly dependent on its coordination environment and the distance between the Mn 2+ ions . The tetrahedral coordination Mn 2+ shows a green emission (500–550 nm) with narrow full width at half-maximum (fwhm) (25–60 nm) while the octagonal coordination Mn 2+ shows an orange-red emission (>600 nm) with broad fwhm (>60 nm). , Nevertheless, the d–d transition of Mn 2+ , determined by spin and parity selection rules, is concentration-dependent with Mn–Mn coupling at high concentrations resulting in low photoluminescence quantum yield (PLQY) .…”

Competing Energy Transfer in Two-Dimensional Mn2+-Doped BDACdBr4 Hybrid Layered Perovskites with Near-Unity Photoluminescence Quantum Yield

“…In recent years, two-dimensional (2D) halogenated layered perovskites have attracted extensive attention due to their high photoluminescence (PL) quantum yield (QY), high carrier mobility, long exciton diffusion length, and outstanding stability. − This class of materials has been used in solar cells, − light-emitting diodes (LEDs), − and photodetectors, − demonstrating excellent optoelectronic performance. More recently, 2D hybrid layered perovskites (HLPs) with covalently bonded metal monolayers have shown tunable electronic and optical properties of interest for various photonic applications. , The assembly of organic cations can not only expand the diversity of 2D layered perovskites but also modulate the band structure and photophysical properties. − Therefore, in-depth understanding of the fundamental optoelectronic properties of 2D HLPs is highly desired. , …”