Lithium-doping enhanced WO3 photoanodes: Reduced carrier loss and extended collection length

Abstract

Photoelectrochemical (PEC) solar-fuel conversion represents a promising approach for efficiently capturing and storing solar energy. WO3 is extensively utilized as a PEC photoanode, but its performance is constrained by small polaron hopping dominated carrier losses. This study comprehensively investigates the enhancement of WO3 photoanode performance through lithium (Li)-doping. The results demonstrate that Li-doping significantly enhances charge mobility and reduces charge transfer resistance, thereby enabling a photocurrent of 0.98 mA cm−2 at 1.4 V vs RHE, 2.51-fold larger than the pristine WO3. Carrier distributions and loss characteristics were quantified using the optical transfer matrix method and incident photon-to-electron conversion efficiency measurements. These analyses reveal that Li-doping effectively suppresses carrier loss within the WO3 film and extends the carrier collection length by 8 nm, leading to significantly enhanced PEC performance. This work provides deeper insights into the charge dynamics of WO3 photoanodes, synergistically integrates experimental characterization with optoelectronic modeling, and lays a theoretical foundation for high-performance PEC device design.