The study explores the crucial role of trace oxygen in organic semiconductors (OSCs) and develops a non-destructive deoxygenation method (de-doping) using soft plasma treatment. Traditional deoxygenation methods, such as annealing and sublimation, are shown to leave trace oxygen residues, questioning the current understanding of oxygen's role. The research reveals that trace oxygen pre-empts donor-like traps in OSCs, leading to p-type characteristics, which is contrary to the previously reported carrier trapping. De-doping results in the disappearance of p-type behaviors and a significant increase in n-type properties, while re-doping under light irradiation in O₂ can reverse these changes. This method allows for precise modulation of key electronic characteristics, such as polarity, conductivity, threshold voltage, and mobility, without destructive effects. The findings provide a new perspective on the intrinsic properties and perplexing observations of OSCs and offer a practical way to modulate charge transport in OSCs, potentially advancing the organic electronics industry.The study explores the crucial role of trace oxygen in organic semiconductors (OSCs) and develops a non-destructive deoxygenation method (de-doping) using soft plasma treatment. Traditional deoxygenation methods, such as annealing and sublimation, are shown to leave trace oxygen residues, questioning the current understanding of oxygen's role. The research reveals that trace oxygen pre-empts donor-like traps in OSCs, leading to p-type characteristics, which is contrary to the previously reported carrier trapping. De-doping results in the disappearance of p-type behaviors and a significant increase in n-type properties, while re-doping under light irradiation in O₂ can reverse these changes. This method allows for precise modulation of key electronic characteristics, such as polarity, conductivity, threshold voltage, and mobility, without destructive effects. The findings provide a new perspective on the intrinsic properties and perplexing observations of OSCs and offer a practical way to modulate charge transport in OSCs, potentially advancing the organic electronics industry.