**5. Optoelectronics applications of perovskite**

#### **5.1 Optical lasing**

High absorption coefficient and strong photoluminescence is the most powerful side of metal halide perovskite. It is possible to obtain a laser with a high quantum efficiency material and a suitable optical band spacing. With the understanding

that amplified spontaneous emission can be obtained from perovskite material, research has focused on this subject. Especially, laser obtaining studies were carried out by using perovskite crystal. It has also been shown that perovskite nanowires in high crystalline feature can have a Fabry-Perot gap to obtain a laser in the material [88]. By manipulating the content of the halide in the composition of the perovskite lead to control the emission wavelength and obtain the laser in the entire visible spectrum (**Figure 12a** and **b**) [57]. Zhu et al. showed that laser exposure in CH3NH3 PbX3 with an exponentially low current threshold (220 nJ cm−2) and a corresponding carrier density as low as 1.5 × 1016 cm−3.
