Rasel Md Abu Jafar, Giri Ashutosh, Olson David H, Ni Chaoying, Hopkins Patrick E, Feser Joseph P
Department of Mechanical Engineering, University of Delaware, Newark, Delaware 19716, United States.
Department of Mechanical, Industrial and Systems Engineering, University of Rhode Island, Kingston, Rhode Island 02881, United States.
ACS Appl Mater Interfaces. 2020 Dec 2;12(48):53705-53711. doi: 10.1021/acsami.0c10894. Epub 2020 Nov 17.
In 2D organic-inorganic hybrid perovskite materials, layers of conducting inorganic material are separated by insulating organic spacers whose length and composition can be tuned. We report the heat capacity and cross-plane thermal conductivity of 2D alkylammonium lead iodide single crystals with increasing chain length, (CHNH)PbI ( = 4-7). The measured thermal conductivities are some of the lowest ever recorded for single crystals, with averages in the range = 0.099-0.125 W/m K. Although a model based on independent interface resistances between adjacent layers predicts an increase in thermal conductivity with a chain length of more than 30%, experimentally we find that the thermal conductivity is nearly independent of chain length and possibly decreases. We hypothesize that phonons carry an appreciable portion of the heat across the interface coherently, rather than being limited by individual weak interfaces.
在二维有机-无机杂化钙钛矿材料中，导电无机材料层被绝缘有机间隔层隔开，有机间隔层的长度和组成可以调节。我们报告了链长增加的二维烷基铵碘化铅单晶（(CHNH)PbI，n = 4 - 7）的热容和平面内热导率。测量得到的热导率是单晶有史以来记录到的一些最低值，平均值在0.099 - 0.125 W/m·K范围内。尽管基于相邻层之间独立界面电阻的模型预测热导率会随着链长增加超过30%，但实验中我们发现热导率几乎与链长无关，甚至可能降低。我们推测声子在界面上相干地携带了相当一部分热量，而不是受限于单个弱界面。
