Enhancing Photocurrent by High‐Transmittance Porphyrin‐Based Hole Transport Materials in Organic Photovoltaics

ABSTRACT In organic photovoltaics (OPVs), the light absorption of hole transport layer (HTL) leads to significant photon loss, thereby limiting the overall device performance. Particularly in semitransparent devices, HTL light absorption further reduces the average visible transmittance (AVT). To address this issue, this study synthesized a novel porphyrin‐based HTL material TCPP‐Zn. Due to the intrinsic light‐absorbing nature of porphyrins, TCPP‐Zn exhibits high transparency in most of the visible spectrum with characteristic absorption at the Soret band, surpassing that of the conventional HTL PEDOT:PSS. This inherent high transparency enables that more photons can pass through the HTL and be absorbed by the active layer, thereby effectively enhancing the short‐circuit current density ( J _SC ). In opaque devices with D18:L8‐BO active layer, the TCPP‐Zn‐based devices show a higher power conversion efficiency (PCE) of 18.3% than PEDOT:PSS‐based control devices (18.0%). In semitransparent devices with PM6:BTP‐eC9 active layer, the TCPP‐Zn‐based devices attain a PCE of 13.5%, an AVT of 28.2% and a light utilization efficiency (LUE) of 3.82%, outperforming the control devices based on PEDOT:PSS (PCE = 13.3%, AVT = 26.8%, LUE = 3.56%). This work demonstrates the potential of porphyrin‐based materials as high‐performance HTLs in OPVs and provides insights for the design of future interfacial materials.