## 2 Amplified Spontaneous Emission
### Perovskites Nanocrystals Thin Films
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Active Material** & **Threshold** & \begin{tabular}{c} **Peak wav.** \\ **(nm)** \\ \end{tabular} & \
\begin{tabular}{c} **Pump Pulse** \\ **Length** \\ \end{tabular} &
\begin{tabular}{c} **Pump wav.** \\ **(nm)** \\ \end{tabular} & **Ref.** \\ \hline MAPbI\({}_{3}\) & 26.5 \(\upmu\)cm\({}^{-2}\) & 793 & 120 fs & 520 & [15] \\ MAPbI\({}_{3}\) & 12 \(\upmu\)cm\({}^{-2}\) & 788 & 150 fs & 600 & [4] \\ MAPbI\({}_{3}\) & 7.6 \(\upmu\)cm\({}^{-2}\) & 780 & 5 ns & 532 & [12] \\ MAPbI\({}_{3}\) & 54.1 \(\upmu\)cm\({}^{-2}\) & \(\approx\)780 & 5 ns & 500 & [16] \\ MAPbI\({}_{3}\) & 47 \(\upmu\)cm\({}^{-2}\) & 793 & 7 ns & 520 & [15] \\ MAPbI\({}_{3}\)-PMMA & 16.9 \(\upmu\)cm\({}^{-2}\) & 793 & 120 fs & 520 & [15] \\ MAPbI\({}_{3}\)-PMMA & 600 \(\upmu\)cm\({}^{-2}\) & \(\approx\)780 & 1 ns & 533 & [19] \\ MAPbI\({}_{3}\)-PMMA & 31 \(\upmu\)cm\({}^{-2}\) & 793 & 7 ns & 520 & [15] \\ MAPbI\({}_{3}\)-\(\upmu\)C\({}_{3}\) & 50 \(\upmu\)cm\({}^{-2}\) & \(\approx\)800 & 0.88 ns & 337 & [20] \\ MAPbBr\({}_{3}\) & 303 \(\upmu\)cm\({}^{-2}\) & 549 & 1 ns & 355 & [13] \\ MAPbBr\({}_{3}\) & 45 \(\upmu\)cm\({}^{-2}\) & \(\approx\)552 & 1 ns & 355 & [18] \\ MAPbBr\({}_{3}\) & 35 \(\upmu\)cm\({}^{-2}\) & 550 & 5 ns & 444 & [17] \\ MAPbBr\({}_{3}\)-PMMA & 140 \(\upmu\)cm\({}^{-2}\) & 549 & 1 ns & 355 & [13] \\ FAPbI\({}_{3}\) & 3.0 \(\upmu\)cm\({}^{-2}\) & 812 & 150 fs & 400 & [21] \\ FAPbI\({}_{3}\) & 19.5 \(\upmu\)cm\({}^{-2}\) & 812 & 5 ns & 532 & [21] \\ CsPbBr\({}_{3}\) & 3.3 \(\upmu\)cm\({}^{-2}\) & \(\approx\)545 & 150 fs & 400 & [23] \\ CsPbBr\({}_{3}\) & 12.5 \(\upmu\)cm\({}^{-2}\) & 541 & 300 ps & 355 & [24] \\ CsPbBr\({}_{3}\) & 26 \(\upmu\)cm\({}^{-2}\) (10 K) & 534 & 3 ns & 337 & [22] \\ CsPbBr\({}_{3}\) & 64.9 \(\upmu\)cm\({}^{-2}\) & \(\approx\)545 & 5.5 ns & 355 & [23] \\ CsPbCl\({}_{3}\) NCs & 10.9 \(\upmu\)cm\({}^{-2}\) & 460 & 100 fs & 400 & [5] \\ CsPbCl\({}_{1,4}\)Br\({}_{1,6}\) NCs & \(\approx\)48 \(\upmu\)cm\({}^{-2}\) & 475 & 100 fs & 400 & [29] \\ CsPbBr\({}_{3}\) (OA) NCs & 193.5 \(\upmu\)cm\({}^{-2}\) & 538 & 50 fs & 400 & [36] \\ CsPbBr\({}_{3}\) (DA) NCs & 89.76 \(\upmu\)cm\({}^{-2}\) & 538 & 50 fs & 400 & [36] \\ CsPbBr\({}_{3}\) NCs & 2 \(\upmu\)cm\({}^{-2}\) & 535 & 100 fs & 400 & [35] \\ CsPbBr\({}_{3}\) NCs & 5.3 \(\upmu\)cm\({}^{-2}\) & 530 & 100 fs & 400 & [5] \\ CsPbBr\({}_{3}\) NCs & \(\approx\)38 \(\upmu\)cm\({}^{-2}\) & 502 & 100 fs & 400 & [29] \\ CsPbBr\({}_{3}\) NCs & 450 \(\upmu\)cm\({}^{-2}\) & 530 & 10 ns & 355 & [5] \\ CsPbBr\({}_{3}\) nanorod & 7.5 \(\upmu\)cm\({}^{-2}\) & 534 & 1 ns & 355 & [38] \\ CsPbBr\({}_{3}\)\({}_{2,2}\) NCs & \(\approx\)55 \(\upmu\)cm\({}^{-2}\) & 620 & 100 fs & 400 & [29] \\ CsPbI\({}_{3}\) NCs & 22 \(\upmu\)cm\({}^{-2}\) & 630 & 100 fs & 400 & [5] \\ MAPbBr\({}_{3}\) NCs & 3 \(\upmu\)cm\({}^{-2}\) & 545 & 100 fs & 400 & [31] \\ MAPbBr\({}_{3}\) NCs & 14 \(\upmu\)cm\({}^{-2}\) & 548 & 150 fs & 400 & [37] \\ FAPbI\({}_{3}\) NCs & 7.5 \(\upmu\)cm\({}^{-2}\) & 808 & 100 fs & 400 & [33] \\ FAPbI\({}_{3}\) NCs & 140 \(\upmu\)cm\({}^{-2}\) & 808 & 4 ns & 532 & [34] \\ FA\({}_{0,1}\)Cs\({}_{0,9}\)PbI\({}_{3}\) NCs & 28 \(\upmu\)cm\({}^{-2}\) & 720 & 100 fs & 400 & [33] \\ \hline \hline \end{tabular}
\end{table} 
Table 1: ASE properties of the perovskites described in this review. The data are grouped according to the active material and in order of increasing pump pulse time length. For papers discussing multiple samples with the same material the reported data are relative to the sample with the minimum threshold. Figure 3: **(a)**: TEM image of CsPbBr\({}_{3}\) nanorods. **(b)**: excitation density dependence of the PL spectra. **(c)**: Excitation density dependence of PL spectrum intensity and linewidth. Adapted with permission from [38]. American Chemical Society, 2019.