Lead antimony sulfide (Pb₅Sb₈S₁₇) solid-state quantum dot-sensitized solar cells with an efficiency of over 4%

Lead antimony sulfides are rare in nature and relatively unexplored ternary semiconductors. This work investigates the photovoltaic performance of Pb-Sb-S quantum dot-sensitized solar cells (QDSCs). Pb₅Sb₈S₁₇ nanoparticles are grown on mesoporous TiO₂ electrodes using the successive ionic layer adsorption reaction process. The synthesized Pb₅Sb₈S₁₇ nanoparticles exhibit two attractive features for a good solar absorber material: a high optical absorption coefficient and a near optimal energy gap. Solid-state QDSCs are fabricated from the synthesized Pb₅Sb₈S₁₇ nanoparticles using Spiro-OMeTAD as the hole-transporting material. The best cell yields a short-circuit current density J_sc of 11.92 mA cm^-2, an open-circuit voltage V_oc of 0.48 V, a fill factor FF of 30.7% and a power conversion efficiency (PCE) of 1.76% under 1sun. The external quantum efficiency (EQE) spectrum covers a spectral range of 350-800 nm with a maximal EQE = 65% at λ = 450 nm. At the reduced light intensity of 10% sun, the PCE increases to 4.14% with J_sc = 2.0 mA cm^-2 (which could be normalized to 20 mA cm^-2 under 1 sun). This PCE is 65% higher than the best previous result. The respectable PCE and J_sc indicate that Pb₅Sb₈S₁₇ could be a potential candidate for a solar absorber material.