Generation of Amplified Spontaneous Emission in Lead Halide Perovskite Semiconductors

Abstract

Lead halide perovskites (LHPs) have arisen as a new class of semiconductors with excellent perspectives to become an alternative to traditional III–V epitaxial nanostructures for applications in active photonics. From the earliest demonstration of amplified spontaneous emission (ASE) with CH3NH3PbX3 (X = Cl, Br, I) polycrystalline thin films in 2014, more than 200 papers have been published in this field with regards to the improvement of the ASE figures of merit or the understanding of the underlaying physical mechanisms in the generation of optical gain for different LHPs. This extraordinary progress has resulted in the synthesis of either CH3NH3PbX3 perovskites as polycrystalline thin films or layers made of fully inorganic CsPbX3 perovskite nanocrystals (PNCs) that can be integrated in different optical architectures or substrates using cheap and straightforward solution processing techniques. Consequently, ASE with thresholds smaller than a few nJ cm−2 or lasing under continuous wave operation, among other impressive results, have been recently achieved. The role of the radiative recombination time, nonradiative traps, Auger recombination, excitation fluency, and absorption coefficient are discussed in this chapter within the framework of available studies and results in the literature, as well as in the light of our own work. This chapter will also review the most important results obtained by the scientific community in the field of active photonic devices and integrated concepts based on LHPs, which contain the integration of bulk polycrystalline and PNC thin films on different substrates, even those which are flexible. Spontaneous emission and ASE will be discussed based on a rate equation model incorporated into a beam propagation algorithm, in the case of optical waveguides, to simulate the generation and propagation of emitted light and optical gain, as an important tool toward the design of active integrated photonics based on LHPs.

Tailoring Single‐Mode Random Lasing of Tin Halide Perovskites Integrated in a Vertical Cavity

“…Contrarily, from spontaneous emission to lasing regime an abrupt decrease in the spectrum linewidth is observed down to 3-8 meV, depending on the studied cases, which is characteristic of the optical gain generation (Figure 2f). [34] More interestingly, the values of P th deduced from Figure 2d-f are in the range of 35-700 μJ cm −2 , see dashed lines, suggesting an optimum E 0 in the range 1.42-1.45 eV, where RL or VL is enhanced. Besides, for E 0 = 1.40 eV, the mode is perfectly overlapped with the PL maximum and hence the cavity is presenting the maximum Purcell effect, [35][36][37] as shown in Figure S5 porting Information) (continuous line), which is the reason of the observation of monomode VL (Figure 2a,b) with a linewidth limited by the cavity Q-factor.…”

“…Contrarily, from spontaneous emission to lasing regime an abrupt decrease in the spectrum linewidth is observed down to 3–8 meV, depending on the studied cases, which is characteristic of the optical gain generation (Figure 2f). [ 34 ]…”

“…Counterintuitively, in microcavities with E 0 in the energy range 1.35–1.37 eV (see the statistics plotted in Figure 2g), RL lines are also observed, but P th lies in the range 100–200 µJ cm⁻ 2 , higher than minimum values of P th = 10–40 µJ cm⁻ 2 for the case of microcavities with resonant modes at E 0 = 1.42–1.45 eV. In both cases, RL lines are vertically outcoupled, which is attributed to the overlapping of M0 with the absorption band edge (X) instead of the PL maximum, where the semiconductor would be presenting a maximum of absorption/optical gain [ 34 ] without noticeable reabsorption of emitted light. Here, emitted light coupled to M0 experiences an important enhancement, as estimated experimentally in Figure S5 (Supporting Information).…”