Spacer Switched Two-Dimensional Tin Bromide Perovskites Leading to Ambient-Stable Near-Unity Photoluminescence Quantum Yield

Abstract

Semiconductor nanostructures with near-unity photoluminescence quantum yields (PLQYs) are imperative for light-emitting diodes and display devices. A PLQY of 99.7 ± 0.3% has been obtained by stabilizing 91% Sn2+ in the Dion–Jacobson (8N8)­SnBr4 (8N8-DJ) perovskite with 1,8-diaminooctane (8N8) spacer. The PLQY is favored by a longer spacer molecule and out-of-plane octahedral tilting. The PLQY shows one-month ambient stability under high relative humidity (RH) and temperature. With n-octylamine (8N) spacer, Ruddlesden–Popper (8N)2SnBr4 (8N-RP) also shows PLQY of 91.7 ± 0.6%, but it has poor ambient stability. The 5–300 K PL experiments decipher the self-trapped excitons (STEs) where the self-trapping depth is 25.6 ± 0.4 meV below the conduction band because of strong carrier–phonon coupling. The microsecond long-lived STE dominates over the band edge (BE) peaks at lower excitation wavelengths and higher temperatures. The higher PLQY and stability of 8N8-DJ are due to the stronger interaction between SnBr6 4– octahedra and 8N8 spacer, leading to a rigid structure.

Perovskite Nanostructure Films for Optoelectronics and Photovoltaics

“…These features are in stark contrast to the broad and redshifted self-trapped excitonic (STE) emission bands. 36 The optical properties of the AIP NCs mostly remain unchanged between the dispersed solution and the films, prepared by drop-casting or spin-coating the NC solutions (Figure 2a). 29 It has been observed that the absorption and emission spectra of the CsPbBr 3 NCs shift to energies lower than those of the corresponding NSs, because of a NC edge length higher than the NS thickness (Figure 2b).…”

“…39 With a lowering of temperature, the number of phonon modes of 2D or 3D perovskites decreases, and at a temperature of ∼10 K, the line width is due to the inhomogeneous broadening. 36…”

“…36 Despite the LEDs having a particular color (red, orange, green, or blue), the perovskites can be employed in white light LEDs either by forming CsPbX 3 NC composites 75 or with the systems that display STE emission over a broad wavelength range. 36,76 The environment-friendly perovskite phosphors are considered the future candidates in display technologies. In the case of PSCs, although the PCE of the NC-based PSC is subservient to the bulk PSCs, suitable antisolvent treatment and passivation can propel the PCE beyond its projected limitations.…”

The Effects of Mono- and Bivalent Linear Alkyl Interlayer Spacers on the Photobehavior of Mn(II)-Based Perovskites

“…Among these alternatives, Sn-based perovskites showed great potential, but unfortunately, the rapid oxidations of Sn 2+ and Sn 4+ drastically hinder their stability and, hence, their applicability [ 10 , 11 , 12 ]. However, for 2D Sn-based Ruddlesden-Popper perovskites, the sizes and configurations of organic spacer cations have remarkable effects on the properties of these materials [ 13 , 14 ].…”

Zn(II) Alloying Improves the Luminescence Efficiency of Hybrid Tetrahedral Mn(II) Halides ((DMAPH)2MnX4; X = Cl, Br, and I) to Near-Unity

“…Zero-dimensional (0D) metal–organic hybrids (MOH) have received increasing attention in research areas including light-emitting diodes (LED), photodetectors, and scintillators because of their excellent optoelectronic properties and high photoluminescence quantum yields. − It has been demonstrated that Pb 2+ - and Sn 2+ -based hybrid systems show excellent PLQY and remarkable performance in X-ray scintillation. ,, However, while the toxicity of lead (Pb 2+ ) limits their industrial applications, Sn 2+ -based systems suffer from poor stability, even in the presence of a trace amount of moisture. , Subsequently, 0D hybrids based on Co 2+ , Ge 2+ , Bi 3+ , etc. were also explored, but the low PLQY and poor stability of these systems are the major bottlenecks. − Recently, Mn 2+ -based 0D hybrid materials have shown great promise in light-emitting diode and photodetector applications, due to their greater stability and extremely high PLQY. ,− The emission color of Mn 2+ depends on its coordination environment, and the emission arises from the d–d spin-forbidden 4 T 1 → 6 A 1 transition.…”