Synthesis, Characterization, and Electrical Properties of CdO-Doped Polyaniline for Enhanced Hole Extraction and Performance in Inverted Perovskite Solar Cells

Abstract

PEDOT: PSS is recognized as one of the most conductive polymers used as an organic hole transport layer (HTL) in inverted perovskite solar cell (PSC) structures. However, its acidic nature and valence band mismatch with the adjacent perovskite layer often led to reduced efficiency and lower open-circuit voltage (VOC) in PSCs. To address these limitations, we incorporated polyaniline (PANI) doped with varying amounts of CdO (x = 0, 1, 5, and 10%), referred to as PANI-CdO (x%). The synthesized CdO samples were thoroughly characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Electrical measurements demonstrated that the addition of CdO enhanced the conductivity and mobility of PANI, contributing to the improved performance of the PSCs. Specifically, the device incorporating the CdO (5%)-doped PANI exhibited superior power conversion efficiency (PCE) of 14.71%, compared to 13.38% for the pristine PEDOT: PSS device. Additionally, VOC increased from 1.02 V (pristine PEDOT: PSS) to 1.11 V (CdO 5% doped PANI), reflecting better energy band alignment and reduced recombination losses. Furthermore, the short-circuit current density (JSC) also improved from 17.01 mA/cm2 to 17.67 mA/cm2, indicating enhanced charge extraction and transport efficiency.