Extraction of PEDOT:PSS/c‐Si Junction Properties by Modeling of Injection‐Dependent Lifetime Measurements Including Depletion Region Modulation

The carrier lifetime of n‐type silicon wafers coated with the conducting polymer PEDOT:PSS as a function of the excess carrier concentration Δ p within the wafer is characterized using the quasi‐steady‐state photoconductance (QSSPC) method, and a drastic increase in the measured apparent lifetime τ app with decreasing Δ p is observed. The observed increase with the depletion region modulation (DRM) effect is explained, as PEDOT:PSS‐coated p‐type silicon wafers do not show any increase in lifetime toward low injection levels. By modeling the measured τ app (Δ p ) curves on n‐type silicon including interface recombination as well as the DRM effect, the interface recombination velocity as well as the band bending Ψ s within the silicon induced by PEDOT:PSS are able to be extracted. The impact of adding sorbitol to the PEDOT:PSS dispersion on the τ app (Δ p ) curves is examined, and it is demonstrated that the admixture of sorbitol improves chemical interface passivation but leaves the band bending within the silicon bulk toward the PEDOT:PSS/c‐Si interface unaffected.