Dominant factors limiting the optical gain in layered two-dimensional halide perovskite thin films

Abstract

Semiconductors are ubiquitous gain media for coherent light sources. Solution-processed three-dimensional (3D) halide perovskites (e.g., CH3NH3PbI3) with their outstanding room temperature optical gain properties are the latest members of this family. Their two-dimensional (2D) layered perovskite counterparts with natural multiple quantum well structures exhibit strong light-matter interactions and intense excitonic luminescence. However, despite such promising traits, there have been no reports on room temperature optical gain in 2D layered perovskites. Herein, we reveal the challenges towards achieving amplified spontaneous emission (ASE) in the archetypal (C6H5C2H4NH3)2PbI4 (or PEPI) system. Temperature-dependent transient spectroscopy uncovers the dominant free exciton trapping and bound biexciton formation pathways that compete effectively with biexcitonic gain. Phenomenological rate equation modeling predicts a large biexciton ASE threshold of ∼1.4 mJ cm(-2), which is beyond the damage threshold of these materials. Importantly, these findings would rationalize the difficulties in achieving optical gain in 2D perovskites and provide new insights and suggestions for overcoming these challenges.

Research Update: Challenges for high-efficiency hybrid lead-halide perovskite LEDs and the path towards electrically pumped lasing

“…110 Exciton trapping and bound bi-exciton pathways compete detrimentally with the desired bi-excitonic optical gain, meaning that achieving lasing in 2D materials through the above mechanism is a fair distance away.…”

Broadband Extrinsic Self‐Trapped Exciton Emission in Sn‐Doped 2D Lead‐Halide Perovskites

“…[20,41,[43][44][45][46][47][48] As a semiconductor of large binding energy (220 meV [43] ), the luminescence of PEA 2 PbI 4 is determined by the dynamics of excitons confined in the inorganic layer, as shown in Figure 1a and Figure S5 (Supporting Information). [20,41,[43][44][45][46][47][48] As a semiconductor of large binding energy (220 meV [43] ), the luminescence of PEA 2 PbI 4 is determined by the dynamics of excitons confined in the inorganic layer, as shown in Figure 1a and Figure S5 (Supporting Information).…”

“…[20,41,[43][44][45][46][47][48] As a semiconductor of large binding energy (220 meV [43] ), the luminescence of PEA 2 PbI 4 is determined by the dynamics of excitons confined in the inorganic layer, as shown in Figure 1a and Figure S5 (Supporting Information). [46,47] With 0.36%-Sn doping in the 2D perovskite, a bright broad red-to-NIR emission band was observed with a full width at half maximum (FWHM) of ≈180 nm at the center of ≈710 nm, while the original green emission almost disappears (Figure 1c,d). [46,47] With 0.36%-Sn doping in the 2D perovskite, a bright broad red-to-NIR emission band was observed with a full width at half maximum (FWHM) of ≈180 nm at the center of ≈710 nm, while the original green emission almost disappears (Figure 1c,d).…”

“…Meanwhile, another peak emerges at around 545 nm with significantly higher intensity than that of the free excitons, resulting in an increase of PL integrated intensity by 28.7 folds. [19] In the pure perovskites, the nature of these bound states is still under debate, [45,47,48,51] with a probable origin being the defects, mainly organic vacancies, which are located at the interface between inorganic and organic layers. The continuous spectral evolution can exclude the phase transition during 25-300 K, similar to previous results of perovskite films.…”

Unveiling the Nature of Charge Carrier Interactions by Electroabsorption Spectroscopy: An Illustration with Lead-Halide Perovskites

“…[4] The term perovskite originally designated calcium titanate CaTiO 3 and is now generalized to all compounds that exhibit an ABX 3 crystal structure in the form of corner-sharing BX 6 [5][6][7][8][9][10][11][12][13][14][15][16] Such a wide range of applications implies a wide range of shapes and structure, and, indeed, although mostly exploited in the form of semiconductor thin-films, lead-halide perovskites can be found as nanocrystals or colloidal nanoparticles, retaining their 3D geometry, as well as quantum-confined, 2D or quasi-2D layers.…”