The incident photon-to-current conversion efficiency (IPCE) analysis was performed at 0 VRHE to reveal the light-harvesting capabilities of both Sb2Se3 photocathodes in the wavelength range of 400 -1100 nm, as shown in Figure . The Sb2Se3-H photocathode shows an outstanding enhancement in photon-harvesting ability compared to the Sb2Se3-L photocathode across the entire spectral region. The IPCE value of the Sb2Se3-L photocathode remains below 68%, while the IPCE value of the Sb2Se3-H photocathode exceeds 68% across the visible spectrum (400 -800 nm) and reaches 91% under 420 nm illumination. The integrated photocurrent density for the Sb2Se3-L and Sb2Se3-H devices, calculated from the IPCE curves using the solar AM 1.5 G spectrum, yields 16.9 mA cm -2 and 24.7 mA cm -2 , respectively. Both integrated photocurrents agree well with the values determined from LSV measurements. The photocurrent density of the photoelectrode can be analyzed by equation 1,