Unusual Spectrally Reproducible and High Q-Factor Random Lasing in Polycrystalline Tin Perovskite Films.

An unusual spectrally reproducible near-IR random lasing (RL) with no fluctuation of lasing peak wavelength is disclosed in polycrystalline films of formamidinium tin triiodide perovskite, which have been chemically stabilized against Sn to Sn oxidation. Remarkably, a quality Q-factor as high as ≈10 with an amplified spontaneous emission (ASE) threshold as low as 2 µJ cm (both at 20 K) are achieved. The observed spectral reproducibility is unprecedented for semiconductor thin film RL systems and cannot be explained by the strong spatial localization of lasing modes.

Spray-driven halide exchange in solid-state CsPbX nanocrystal films.

CsPbI perovskite nanocrystals (NCs) are promising building blocks for photovoltaics and optoelectronics. However, they exhibit an essential drawback in the form of phase stability: α-phase, with a ∼1.80 eV bandgap, can easily experience a phase transition to a non-radiative orthorhombic δ-phase in an ambient environment.

Tin perovskite solar cells with >1,300 h of operational stability in N through a synergistic chemical engineering approach.

Despite the promising properties of tin-based halide perovskites, one clear limitation is the fast Sn oxidation. Consequently, the preparation of long-lasting devices remains challenging. Here, we report a chemical engineering approach, based on adding Dipropylammonium iodide (DipI) together with a well-known reducing agent, sodium borohydride (NaBH), aimed at preventing the premature degradation of Sn-HPs.

Inhomogeneous Broadening of Photoluminescence Spectra and Kinetics of Nanometer-Thick (Phenethylammonium)PbI Perovskite Thin Films: Implications for Optoelectronics.

An outstanding potentiality of layered two-dimensional (2D) organic-inorganic hybrid perovskites (2DHPs) is in the development of solar cells, photodetectors, and light-emitting diodes. In 2DHPs, an exciton is localized in an atomically thin lead(II) halide inorganic layer of sub-nanometer thickness as in a quantum well sandwiched between organic layers as energetic and dielectric barriers. In previous years, versatile optical characterization of 2DHPs has been carried out mainly for thin flakes of single crystals and ultrathin (of the order of 20 nm) polycrystalline films, whereas there is a lack of optical characterization of thick (hundreds of nanometers) polycrystalline films, fundamentals for fabrication of devices.