Surfaces and interfaces in sensors and photovoltaic devices

传感器和光伏器件的表面和界面

• 批准号: RGPIN-2019-04861
• 负责人: Hill, Ian
• 金额: $ 2.48万
• 依托单位: Dalhousie University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=763163
• 关键词: Surfaces; interfaces; sensors; photovoltaic; devices

Surfaces and interfaces control much of the behaviour of electronic and optoelectronic devices, yet they are often ignored, or considered with the most simplistic models when devices are designed and analysed in the laboratory. Typically, the Schottky-Mott and Anderson approximations, which assume vacuum level alignment at metal/semiconductor and semiconductor/semiconductor interfaces, respectively, are assumed in the literature. Despite their wide use, these approximations have been known to be incorrect since 1947 when John Bardeen noted that interfacial alignment would be governed by high densities of interfacial electronic states within the semiconductor gap(s), due to chemical interactions between the two materials, as well as inherent surface states, due to reduced coordination and resulting changes in bonding geometries of atoms at the surface of a material, compared to those in the bulk. These states tend to restrict the movement of the Fermi level within the semiconductor(s) gap(s), and the resulting charges localized near the interface form "interface dipoles", abruptly shifting the vacuum levels. The complexities of the surface caused Wolfgang Pauli to quip, "God made the bulk; surfaces were invented by the devil". "Interface Engineering" is the intentional reaction of a surface with chemical species, or the inclusion of thin interlayers - sometimes one molecule thick - at interfaces in electronic devices in order to modify their properties in advantageous ways. For instance, layers of species with oriented dipole moments can be used to offset the energy levels between two semiconductors, or a semiconductor and a metal, in a way that aids charge injection or extraction. Another application of interface engineering is to affect a change in the way one material deposits on another. An everyday example of this is a freshly-waxed car, where water deposited on the paint no longer spreads out and forms a film, rather, it "beads up". Wax has been used to "engineer" the paint/water interface. Similarly, layers placed on one material (metal, dielectric, substrate), can affect the morphology of a semiconductor film grown on top. In this proposal, we have broadened the typical definition of interface engineering to include interlayers that change the propagation and coupling of light from one material to another. Here we aim to apply our experience with these techniques to three areas of research: 1) using optical interface engineering to enable a new type of sensor that can be use to detect exposure to chemical, biological and radiological threats, 2) studying and modifying the interfaces in printed electronic sensors, and 3) studying and modifying the interfaces in lead-free perovskite solar cells to improve their efficiency through the elimination of charge extraction barriers.

表面和界面控制着电子和光电器件的大部分行为，但在实验室设计和分析器件时，它们往往被忽略，或被认为是最简单的模型。典型地，在文献中假设分别假设金属/半导体和半导体/半导体界面处的真空能级对准的Schottky-Mott和安德森近似。尽管它们被广泛使用，但自1947年以来，这些近似已经被认为是不正确的，当时John Barclay注意到，由于两种材料之间的化学相互作用，界面对准将由半导体间隙内的界面电子态的高密度以及由于减少的配位和导致的材料表面处原子的键合几何形状的变化，相比之下，在大部分。这些状态倾向于限制费米能级在半导体间隙内的移动，并且所产生的位于界面附近的电荷形成“界面偶极子”，突然移动真空能级。表面的复杂性使沃尔夫冈·泡利（Wolfgang Pauli）打趣道：“上帝创造了体积;表面是魔鬼发明的。“界面工程”是表面与化学物质的有意反应，或者在电子设备的界面处包含薄的夹层-有时只有一个分子厚-以便以有利的方式修改它们的特性。例如，具有定向偶极矩的物质层可以用于以有助于电荷注入或提取的方式抵消两个半导体或半导体和金属之间的能级。界面工程的另一个应用是影响一种材料沉积在另一种材料上的方式的变化。这方面的一个日常例子是一辆刚打过蜡的汽车，其中沉积在油漆上的水不再扩散并形成薄膜，而是“珠状”。蜡已被用于“工程师”的油漆/水界面。类似地，放置在一种材料（金属、电介质、衬底）上的层可以影响在其上生长的半导体膜的形态。在这个建议中，我们已经扩大了界面工程的典型定义，包括改变光从一种材料到另一种材料的传播和耦合的夹层。在这里，我们的目标是将这些技术的经验应用于三个研究领域：1）使用光学界面工程，以实现可用于检测化学、生物和放射性威胁的新型传感器，2）研究和修改印刷电子传感器中的界面，以及3）研究和改性无铅钙钛矿太阳能电池中的界面以通过消除电荷提取势垒来提高其效率。