Amplified Spontaneous Emission Based on 2D Ruddlesden–Popper Perovskites

Abstract

Abstract2D Ruddlesden–Popper perovskites (RPPs) are a class of quantum‐well (QW) materials, composed of layered perovskite QWs encapsulated between two hydrophobic organic layers. Different from widely investigated 3D‐perovskites with free carriers at room temperature, 2D‐RPPs exhibit strongly bound electron–hole pairs (excitons) for high‐performance solar cells and light emitting diodes (LEDs). Herein, it is reported that self‐organized multiple QWs in 2D‐RPP thin films naturally form an energy cascade, which enables an ultrafast energy transfer process from higher energy‐bandgap QWs to lower energy‐bandgap QWs. Therefore, photoexcitations are concentrated on lower‐bandgap QWs, facilitating the build‐up of population inversion. Room‐temperature amplified spontaneous emission (ASE) from 2D‐RPP thin films is achieved at dramatically low thresholds, with gain coefficients as high as >300 cm−1, and stoichiometrically tunable ASE wavelengths from visible to near‐infrared spectral range (530–810 nm). In view of the high efficiency reported for LEDs, these solution‐processed 2D‐RPP thin films may hold the key to realize electrically driven lasers.

Two‐Photon Up‐Conversion Photoluminescence Realized through Spatially Extended Gap States in Quasi‐2D Perovskite Films

“…[9][10][11][12] Such 2D perovskites can demonstrate remarkable tunabilities on optical properties via controlling morphological structures by selecting different functional A/A′ molecules. [20] On the other hand, it has been found that the edge states can be formed in 2D perovskites with light-emitting properties below the bandgap. Recently, amplified spontaneous emission (ASE) have been reported in 2D perovskites [(NMA) 2 (FA)Pb 2 Br 7 and (NMA) 2 (FA)Pb 2 Br 1 I 6 ] with stoichiometrically tunable wavelength from visible to near-infrared spectral range (530-810 nm) with the gain coefficient as high as > 300 cm −1 under pulse laser excitation.…”

Stability of Perovskite Light Sources: Status and Challenges

“…[ 73 ] Li et al also improved the stability of amplified spontaneous emission through the naphthylmethylammonium and FA mixed 2D‐RP perovskite thin films. [ 90 ]…”

“…[ 135 ] b) ASE photo stability of (NMA) 2 (FA)Pb 2 Br 1 I 6 films. [ 90 ] The ASE spectrums at the start of the test and after 30 h excitation are illustrated in the inset. c) Photo stabilities of ASE intensity of CsPbBr 3 ‐DA quantum dots (QDs) films.…”

“…The ASE in (C 10 H 7 CH 2 NH 3 ) 2 (HC(NH 2 ) 2 )Pb 2 Br y I 7− y could be maintained after pumping by as many as 1.2 × 10 8 laser pulses as shown in Figure 6b. [ 90 ]…”

“…The ASE in (C 10 H 7 CH 2 NH 3 ) 2 (HC(NH 2 ) 2 ) Pb 2 Br y I 7−y could be maintained after pumping by as many as 1.2 × 10 8 laser pulses as shown in Figure 6b. [90] Ligand-modification strategy is helpful for improving the stability of CsPbBr 3 QDs. Theoretical calculation showed that ligand loss due to weak surface ligands and QD binding energy lead to the problem of poor long-term stability.…”