TAGRA 2025

The hole transport layer (HTL) is a critical component in perovskite solar cells (PSCs), governing charge extraction efficiency and interfacial stability. Molybdenum trioxide (MoO₃), a wide-bandgap transition metal oxide, offers favorable energy alignment and high work function, yet its performance can be further optimized through controlled doping. In this work, lanthanum (La)-doped MoO₃ thin films were synthesized via spin-coating and systematically characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visible spectroscopy (UV-Vis), and electrical measurements. XRD analysis confirmed the orthorhombic α-MoO₃ phase with high crystallinity and phase purity, while peak broadening revealed microstrain and reduced crystallite size, enhancing surface reactivity and charge transfer dynamics. At 3 mol% La doping, the films exhibited the widest optical bandgap (3.58 eV), minimized defect scattering, and peak electrical conductivity, attributed to improved crystallinity and reduced dislocation density. These structural and electronic improvements translated into enhanced carrier mobility and selective hole transport, reducing recombination losses at the perovskite/HTL interface. The findings establish La-doped MoO₃, particularly at 3 mol% concentration, as a promising HTL candidate for stable, high-performance PSC architectures.