Nano-ribbon solar fuel devices

由环境友好、经济高效的太阳能电池产生的能源为满足日益增长的全球能源需求提供了一种可持续的解决方案。因此，研究人员专注于开发薄膜太阳能电池，使用高效、环保、富含地球的吸收材料，如金属硫化物和硒化物。与其他新兴化合物相比，硒化锑（Sb2Se3）由于具有相化学简化、物理化学稳定性高、合适的带隙、高载流子迁移率和高吸收系数等优点，作为一种有前途的光活性材料在光伏领域受到了极大的关注。制备Sb2Se3薄膜采用了不同的物理化学方法，包括快速热蒸发（RTE）、磁控溅射、近距离升华、电沉积、原子层沉积等。当Sb2Se3薄膜沉积在衬底上时，（Sb4Se6）n带表现出不同的生长方向（横向和垂直生长模式），由于其复杂的微观结构，难以控制。在（Sb4Se6）n - 1D链结构中，原子是共价键，而条带是通过范德华力相互连接的。这导致载流子沿（Sb4Se6）n带的迁移速度比带间的迁移速度快。为了在整个Sb2Se3层中提供更好的电荷输运和减少电荷重组，条带应该垂直于衬底。因此，调节Sb2Se3薄膜中（Sb4Se6）n带的横向和纵向生长比例，以保证载流子的高效传输至关重要。因此，本研究的重点是探索高效太阳能电池的最佳Sb2Se3纳米带取向的新生长条件。为了分析一维纳米带的择优取向，利用RTE将Sb2Se3沉积在掺氟氧化锡（FTO）衬底上。为了解Sb2Se3薄膜的生长机理和载流子输运行为，将采用x射线衍射、扫描电镜、透射电镜、表面轮廓仪和开尔文探针力显微镜对Sb2Se3薄膜的结构和性能进行系统表征和分析。此外，还将研究Sb2Se3薄膜对太阳能电池性能的影响。在此，薄膜太阳能电池器件被配置为层状结构，其中薄膜被涂有缓冲层，然后以金属背接触（即Au）的沉积结束。本研究中用于与吸收层形成p-n异质结的缓冲液是n型TiO2。然后，由于在Sb2Se3/TiO2界面之间的p-n异质结处产生了内置电场，光产生的电子从Sb2Se3 （p型）移动到TiO2 （n型）。另一方面，光产生的空穴被p型空穴输运层吸引并被Au收集，这将减少后接触处的复合。最后，将利用改性薄膜的效果来制造高效的水分解装置。

Energy generated from environmentally friendly, cost-effective solar cells offers a sustainable solution to meet the increasing global energy demand. Hence, researchers are focused on the development of thin-film solar cells using highly efficient, environmentally friendly, earth-abundant absorber materials like metal sulfides and selenides. Compared to other emerging compounds, antimony selenide (Sb2Se3) has gained tremendous interest as a promising photoactive material in photovoltaics due to its advantages of simplified phase chemistry, high physiochemical stability, suitable bandgap, high carrier mobility, and high absorption coefficient. Different physio-chemical methods are used to generate Sb2Se3 thin films, which include rapid thermal evaporation (RTE), magnetron sputtering, close-spaced sublimation, electrodeposition, atomic layer deposition, etc. When the Sb2Se3 thin films are deposited onto a substrate, the (Sb4Se6)n ribbons exhibit different growth orientations (lateral and vertical growth modes) which are difficult to control due to their complex microstructures. In the (Sb4Se6)n 1D chain structure, the atoms are covalently bonded, whereas ribbons are interconnected by van der Waals forces. This results in faster migration of carriers along (Sb4Se6)n ribbons than between ribbons. In order to provide improved charge transport and to reduce the charge recombination throughout the Sb2Se3 layer, the ribbons should oriented perpendicular to the substrate. Therefore, it is crucial to regulate the ratio of lateral and vertical growth of (Sb4Se6)n ribbons in Sb2Se3 thin films to ensure efficient carrier transport. Thus, this study focuses to explore novel growth conditions for optimal Sb2Se3 nanoribbon orientation for efficient solar cells. In order to analyze the preferred orientation of 1D nanoribbons, the Sb2Se3 will be deposited onto the fluorine-doped tin oxide (FTO) substrates with the use of RTE. To understand the growth mechanism and carrier transport behavior of Sb2Se3 thin films, the structure, and properties of Sb2Se3 thin films will be systematically characterized and analyzed by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, surface profilometer, and Kelvin probe force microscopy. Moreover, Sb2Se3 thin films on solar cell performance will be investigated. Herein the thin-film solar cells devices are configured in superstrate configuration where the thin film is coated with a buffer layer and then ends with the deposition of metallic back-contact (i.e., Au). The buffer used in this study to form a p-n heterojunction with an absorber layer is n-type TiO2. The photo-generated electrons then move from Sb2Se3 (p-type) to TiO2 (n-type) due to the creation of a built-in electric field at the p-n heterojunction between the Sb2Se3/TiO2 interface. On the other hand, the photo-generated holes are attracted by the p-type hole-transport layer and collected by the Au which will reduce the recombination at the back contact. Finally, the effect of the modified thin films will be used to fabricate efficient water splitting devices.