Obtaining p-type wide bandgap semiconductors operating in the deep UV (DUV) range (λ < 300 nm) is still challenging. However, as a part of this work, we developed novel p-type solution-processed wide bandgap semiconductors based on solution-processed manganese oxide quantum dots (MnO-QDs) with the gap energy exceeding 4 eV synthesized by ultrafast laser ablation, which can be adopted for flexible and solar-blind DUV optoelectronics. We conducted advanced optical, structural, and electrical characterizations, revealing unique properties of this material. Our findings show excellent band alignment between these QDs and other wide bandgap semiconductors, such as GaN and Ga2O3. The high performance of a solar-blind self-powered DUV photodetector based on p−n junction that comprises n-type wide bandgap semiconductors and p-type MnO-QDs is demonstrated.