Fabrication of ZnO Thin Film through Chemical Preparations

Zinc oxide (ZnO) is a compound that has unique physical and chemical properties. It has a direct band gap at 3.4 eV (without dopant), a high bonding energy (60 meV), and a high thermal and mechanical stability at room temperature. Thus, ZnO thin film can be suitably applied in many fields, and it also has many functions such as UV light emitters, hydrophobic coating, transparent thin film in electronic devices, piezoelectric material, transducers, gas-sensing, and a transparent conductive oxide (TCO) layer in thin film solar cells. ZnO thin film could be prepared by many chemical preparations such as chemical bat deposition (CBD), chemical vapor deposition (CVD), sol–gel spin coating, doctor blade, printing deposition, and electrochemical deposition (ED). This chemical process is a low-cost, simple, and easy preparation process to be adjusted or doped by other elements

Metal Oxide Compact Electron Transport Layer Modification for Efficient and Stable Perovskite Solar Cells

Perovskite solar cells (PSCs) have appeared as a promising design for next-generation thin-film photovoltaics because of their cost-efficient fabrication processes and excellent optoelectronic properties. However, PSCs containing a metal oxide compact layer (CL) suffer from poor long-term stability and performance. The quality of the underlying substrate strongly influences the growth of the perovskite layer. In turn, the perovskite film quality directly affects the efficiency and stability of the resultant PSCs. Thus, substrate modification with metal oxide CLs to produce highly efficient and stable PSCs has drawn attention. In this review, metal oxide-based electron transport layers (ETLs) used in PSCs and their systemic modification are reviewed. The roles of ETLs in the design and fabrication of efficient and stable PSCs are also discussed. This review will guide the further development of perovskite films with larger grains, higher crystallinity, and more homogeneous morphology, which correlate to higher stable PSC performance. The challenges and future research directions for PSCs containing compact ETLs are also described with the goal of improving their sustainability to reach new heights of clean energy production