Quantum 2000 X-ray photoelectron spectrometer featuring monochromatic Al Kα radiation, generated from an electron beam operated at 15 kV and 32.3 W. The energy scale of the instrument was calibrated using Au and Cu reference samples. The analysis was conducted at 1×10 -6 Pa, with an electron take off angle of 45° and a pass energy of 23.50 eV. Core level binding energies were determined fitting Voigt profiles (GL30) after Shirley background subtraction. No charge neutralization was used throughout the measurement. The neutralizer was toggled to ensure the samples were sufficiently conductive. The main component of the C 1s emission for the Sb2S3 substrate was found to be at 284.72 eV. The valence band offset was determined using a procedure based on the Kraut method, which is described in more detail by Klein and coworkers. Results and discussion: