High Optical Gain of Solution-Processed Mixed-Cation CsPbBr3 Thin Films towards Enhanced Amplified Spontaneous Emission - Li, Meili; Shang, Qiuyu; Li, Chun; Li, Shuai; Liang, Yin; Yu, Wenjin; Wu, Cuncun; Liyun Zhao; Zhong, Yangguang; Du, Wenna; Wu, Xianxin; Jia, Zhili; et al. (ADVANCED FUNCTIONAL MATERIALS, 2021)