Layered Hybrid Perovskites for Highly Efficient Three‐Photon Absorbers: Theory and Experimental Observation

Abstract

Multiphoton absorption may find many technological applications, such as enhancing the conversion efficiency of solar cells by the utilization of sub‐band‐energy photons, below‐bandgap photodetection through the simultaneous absorption of several infrared photons for photocurrent generation, or light frequency upconversion for high‐resolution, 3D imaging. To enhance multiphoton absorption in semiconducting materials, one of the strategies is to explore low‐dimensional excitons. Here, a quantum perturbation theory on a giant enhancement in three‐photon absorption (3PA) arising from 2D excitons in multilayered crystals of organic–inorganic hybrid perovskites is presented. The maximal 3PA coefficient is predicted to be in the range of 2–7 cm 3 GW −2 at 1100 nm, the largest values reported so far for any 2D and bulk semiconductors at room temperature. Excellent agreement between theory and the experimental findings unambiguously demonstrates a pivotal role in the enhancement of 3PA played by 2D excitons. The theory predicts that the resonant 3PA coefficient should be enhanced further by at least two orders of magnitude with very low temperature. The findings are essential for understanding giant 3PA arising from 2D excitons in layered hybrid perovskites and may open new pathways for highly efficient conversion from infrared light energy to either electrical energy or higher‐frequency light emission/lasing.

Giant and Broadband Multiphoton Absorption Nonlinearities of a 2D Organometallic Perovskite Ferroelectric

“…[ 11 ] It has been theorized that this 2D family enables large 2PA/3PA absorption coefficients, [ 12 ] as exemplified by the following perovskites: (PEA) 2 PbI 4 (2PA, 211.5 cm MW −1 ), [ 13 ] (BA) 2 (FA)Pb 2 Br 7 (2PA, 5.76 × 10 3 cm GW −1 ), [ 14 ] and (BA) 2 PbBr 4 (3PA, ≈7 cm 3 GW −2 ). [ 15 ] Therefore, we endeavored to assess the potential of 2D multilayered hybrid perovskites with strong 5PA effects.…”

Giant Nonlinear Optical Response in 2D Perovskite Heterostructures

“…The dielectric and quantum confinement effect in 2D layered perovskites not only lead to the large exciton binding energy, but also to enhanced optical nonlinearity . The enhanced nonlinear refraction n 2 and nonlinear absorption coefficient β provide the capabilities of high‐power/high‐efficiency NLO applications …”

Nonlinear Photonics Using Low‐Dimensional Metal‐Halide Perovskites: Recent Advances and Future Challenges

“…In addition to the great third‐order nonlinear optical response, low‐dimensional RPPs possess exceptional higher‐order nonlinear optical characteristics like giant 3PA capability. [ 114,117 ] 3PA is a nonparametric fifth‐order nonlinear optical process and correlates with Imχ (5) .…”

“…Very recently, Lu and co‐workers [ 114 ] quantified the 3PA response of the mechanically exfoliated nanosheets of a prototypical RPP, i.e., (CH 3 (CH 2 ) 3 NH 3 ) 2 PbBr 4 ( n = 1, also called 2D metal‐halide perovskites), where the alternating inorganic PbBr 4 2− and organic C 4 H 9 NH 3 3+ layers constitute MQW structure with giant confinement effect, as displayed in Figure a–c. β 3 of the nanosheets (thickness ≈ 140 nm) were quantified to be in range of ≈(0.56–2.5) cm 3 GW −2 over broad spectral range of (900–1200) nm, [ 114 ] as demonstrated in Figure 9b. Strong excitonic resonance peak at ≈1100 nm was demonstrated in the acquired 3PA spectra.…”

“…Analogous to low‐dimensional 3D metal‐halide perovskites, RPPs (including 2D metal‐halide perovskites, n = 1) and 0D metal‐halide perovskites in low dimension possess fascinating third‐order and higher‐order nonlinear optical characteristics. [ 112–120 ] Concretely, giant and tunable third‐order nonlinear optical response such as 2PA, [ 112,115,117,118 ] SA, [ 118 ] THG, [ 116,119 ] nonlinear refraction, [ 118 ] and higher‐order 3PA [ 114,117 ] have been revealed in low‐dimensional RPPs, thanks to the superb excitonic resonance enhancement. Moreover, targeting at further promoting the nonlinear optical properties of 2D metal‐halide perovskites (RPPs, n = 1), the hybrid dielectric structures between them and dielectric microspheres have been developed to achieve cooperative enhancement.…”