- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
A Review on Improving the Quality of Perovskite Films in Perovskite Solar Cells via the Weak Forces Induced by Additives
摘要： It is a challenge to design intelligent thermal metamaterials due to the lack of suitable theories. Here we propose a kind of intelligent thermal metamaterials by investigating a core-shell structure, where both the core and shell have an anisotropic thermal conductivity. We solve Laplace’s equation for deriving the equivalent thermal conductivity of the core-shell structure. Amazingly, the solution gives two coupling relations of conductivity tensors between the core and the shell, which cause the whole core-shell structure to counterintuitively self-?x a constant isotropic conductivity even when the area or volume fraction of the core changes within the full range in two or three dimensions. The theoretical ?ndings on fraction-independent properties are in sharp contrast with those predicted by the well-known e?ective medium theories, and they are further con?rmed by our laboratory experiments and computer simulations. This work o?ers two coupling relations for designing intelligent thermal metamaterials, and they are not only helpful for thermal stabilization or camou?age/illusion, but they also o?er hints on how to achieve similar metamaterials in other ?elds.
关键词： Laplace’s equation,intelligent thermal metamaterials,core-shell structure,anisotropic thermal conductivity,self-fixing behavior
更新于2025-09-11 14:15:04
-
A suspended 3-omega technique to measure the anisotropic thermal conductivity of semiconducting polymers
摘要： Anisotropic thermal conductivity can complicate the performance of semiconducting polymer thin-films in applications such as thermoelectrics and photovoltaics. Anisotropic measurements of low thermal conductivity polymers are challenging, and there are a limited number of appropriate measurement techniques. Suspended film 3-omega is an appropriate technique but has often required unfavorable microfabrication. Herein, we report on the utility of the suspended 3-omega technique that uses shadow masking, and no other microfabrication techniques, in performing anisotropic (in-plane and through-plane) thermal conductivity measurements of polymer films. We report on the necessary conditions for the validity of the 1D suspended-film heat transfer model and provide experimental guidelines for in-plane thermal conductivity measurements of polymer thin-films. Furthermore, for the first time, we report the anisotropic thermal conductivities of N2200 and a low molecular weight P3HT, which are two common n-type and p-type semiconducting polymers. Measured thermal conductivities are compared with predictions from the conventional Cahill-Pohl model and a recent empirical model that more accurately predicts the temperature dependence.
关键词： semiconducting polymers,thermal conductivity measurements,3-omega technique,anisotropic thermal conductivity,shadow masking
更新于2025-09-10 09:29:36