Work function modulated water-soluble anode interlayer with copper-ion doping for precise signal detection in organic photodiodes†

In organic photovoltaics (OPVs) and organic photodetectors (OPDs), anode interfacial layers are crucial factors since they direct hole transport and extraction from the donor to the anode. A copper-ion-doped water-soluble polyelectrolyte with a deep work function (WF) of −4.95 eV is designed in this study, and the qualitative changes in the component and electronic band structure are investigated in detail. Furthermore, the enhancement of light energy harvesting and light signal detection ability enabled by promoted photocurrents and mitigated dark currents is analyzed by introducing optimal Cu:PSS doped PEDOT:PSS as an anode interlayer in OPVs and OPDs, respectively. Particularly, Cu:PSS is incorporated into PEDOT:PSS in various weight ratios, facilitating compositional modulation between the materials. Incorporating an optimal material results in an improved J_SC of 27.74 mA cm⁻² under 1-sun illumination and a suppressed dark current density of 1.97 × 10⁻⁹ A cm⁻² under self-powered conditions. The optimal conditions facilitate favorable thin film morphology, contributing to the enhancement of device performance. Therefore, this study highlights the potential of optimized amounts of the Cu:PSS dopant for simultaneously promoting OPV and OPD performances, providing an efficient approach to realize light energy harvesting and signal detection.