Gualdrón-Reyes Andrés F, Yoon Seog Joon, Barea Eva M, Agouram Said, Muñoz-Sanjosé Vicente, Meléndez Ángel M, Niño-Gómez Martha E, Mora-Seró Iván
Institute of Advanced Materials (INAM), University Jaume I, Avenida de Vicent Sos Baynat, s/n, 12006 Castelló de la Plana, Castellón, Spain.
Centro de Investigaciones en Catálisis (CICAT), Universidad Industrial de Santander, Sede UIS Guatiguará, Piedecuesta, Santander C.P. 681011, Colombia.
ACS Energy Lett. 2019 Jan 11;4(1):54-62. doi: 10.1021/acsenergylett.8b02207. Epub 2018 Nov 27.
Mixed halide perovskites are one of the promising candidates in developing solar cells and light-emitting diodes (LEDs), among other applications, because of their tunable optical properties. Nonetheless, photoinduced phase segregation, by formation of segregated Br-rich and I-rich domains, limits the overall applicability. We tracked the phase segregation with increasing crystalline size of CsPbBr I and their photoluminescence under continuous-wave laser irradiation (405 nm, 10 mW cm) and observed the occurrence of the phase segregation from the threshold size of 46 ± 7 nm. These results have an outstanding agreement with the diffusion length (45.8 nm) calculated also experimentally from the emission lifetime and segregation rates. Furthermore, through Kelvin probe force microscopy, we confirmed the correlation between the phase segregation and the reversible halide ion migration among grain centers and boundaries. These results open a way to achieve segregation-free mixed halide perovskites and improve their performances in optoelectronic devices.
混合卤化物钙钛矿因其可调谐的光学性质，是开发太阳能电池和发光二极管（LED）等其他应用的有前途的候选材料之一。然而，通过形成富溴和富碘的分离域而产生的光致相分离限制了其整体适用性。我们跟踪了CsPbBrI晶体尺寸增加时的相分离及其在连续波激光照射（405nm，10mW/cm²）下的光致发光，并观察到从46±7nm的阈值尺寸开始出现相分离。这些结果与通过发射寿命和分离速率实验计算得到的扩散长度（45.8nm）非常吻合。此外，通过开尔文探针力显微镜，我们证实了相分离与晶粒中心和边界之间可逆卤离子迁移的相关性。这些结果为实现无分离的混合卤化物钙钛矿并提高其在光电器件中的性能开辟了一条途径。
