TAGRA 2024

Highly transparent and uniform planar surfaced Copper Iodide (CuI) film exhibits intriguing morphological properties by presenting Monoethanolamine (MEA) as the green solvent for CuI, thus yielding a comparable outcome of the hole transport layer (HTL) for perovskite solar cell (PSC) applications. The γ-CuI with a zinc-blende structure can be successfully synthesized at a relatively low temperature of 350 °C using a green solvent-based method without additives. This approach significantly reduces fabrication costs by eliminating the need for high-temperature processes, making it a more economical and sustainable option. CuI films are fabricated on top of Indium-doped Tin Oxide (ITO) glass substrates via a simple solution-processable spin coating technique at room temperature conditions and lastly, completed with an annealing process that ranges from 60 °C, 80 °C, 100 °C and 120 °C. The CuI films' structural properties are characterized by scanning electron microscopy and X-ray diffraction to study the growth of grains and epitaxial growth at the preferred crystallographic orientation, respectively. The pristine, sharp-edged nanoflower-like CuI structure annealed at an optimal temperature of 80 °C exhibited excellent conductivity and comparable band gap energy, making it highly suitable for PSC applications. Compared to conventional JCPDS data (00-006-0246), the γ-CuI reveals changes in its crystallographic planes and X-ray diffraction patterns as the annealing temperature increases. Herein, the annealing temperature plays a critical role in influencing the epitaxial growth and structural parameters of CuI, including crystallite size, lattice constant, lattice strain, and dislocation density. Hence, the optimization of annealing temperature is essential to achieve desirable structural properties, making CuI an effective solid-state thin film and a promising hole transport layer for PSC applications.