Third Harmonic Upconversion and Self-Trapped Excitonic Emission in 1D Pyridinium Lead Iodide

Abstract

Hybrid lead halide perovskites have emerged as an important class of optoelectronic materials. A creative choice of "A"-site organic cations produces hybrid perovskites with reduced dimensionality and intriguing light−matter interactions. Nonlinear optical effects are expected to be stronger in one-dimensional (1D) lead halides compared to those in their 2D or 3D analogues due to greater quantum and dielectric confinements. We performed an extensive probe of the third harmonic generation (THG) properties in 1D pyridinium lead iodide single crystals for the first time. An efficient THG with a high laser-induced damage threshold is the highlight of this system. THG is selectively enhanced for excitation at an optical communication wavelength (1.5 μm) corresponding to band gap resonance. A strong exciton−phonon interaction results in highly Stokes-shifted self-trapped excitonic emission in the 5−300 K temperature range. An interplay between anharmonicity and dynamic disorder dictates the emission properties, further complicated by an isostructural phase transition at 170 K.

Effect of chirality on the optical properties of layered hybrid perovskiteR- andS-α-methylbenzylammonium lead iodide

“…S7 (ESI†), the integrated PL intensity in all three samples increases initially upon decreasing the temperature from 300 to 100 K due to the suppression of the thermally activated exciton dissociation and the non-radiative exciton recombination. 26 Below 100 K, the integrated PL intensity reverses its trend, probably due to the trapping of the carriers by some non-emissive states, as reported previously. 27,28 Upon decreasing the temperature, the PL emission of all three samples shows a slight gradual blue shift (Fig.…”

Rational Design of Non-Centrosymmetric Hybrid Halide Perovskites

“…Experimental details for these measurements are provided in the literature and the methods section of Supporting Information. 41,42 Figure 4a shows the spectrally-resolved harmonic generation spectra of (MIPA) 2 PbI 4 single crystals obtained in the range ∼390−790 nm using pump pulses with 1.5 mW power. Interestingly, both SHG and THG are obtained simultaneously, as shown in Figure 4a.…”

Getting the details right: optical, dielectric, and vibrational outcomes of structural phase transition in one-dimensional pyrrolidinium lead iodide and the role of defects

“…Very recently, analogous behaviour of SR-THG responses was noted for 1D lead halide perovskites of pyridinium lead iodide (PyPbI 3 ), which displayed self-trapped excitonic emission. 26 As opposed to these examples, results collected for PyrPbI 3 demonstrate no resonant enhancement of THG at the edge of the band gap, but stabilization of relative THG intensity is observed once third harmonic signals move away from the one-photon absorption band. In other words, the observed wavelength dependence of THG can be predominantly ascribed to harmonic self-absorption and the apparent lack of resonance enhancement of THG that we take as an additional hint that observed broad emission comes from defect-induced states.…”