Transparent perovskite pn junction in ZnCo2O4/SrTiO3 for photoelectric conversion enhancement via barrier transition/upconversion of Tm:Bi2O3 quantum dots

The ZnCo2O4/Tm:Bi2O3 quantum dots/SrTiO3 transparent perovskite pn junction is synthesized via the approach of a hybrid chemical-sol-gel-annealing method. The as-prepared ZnCo2O4/Tm:Bi2O3 QDs/SrTiO3 shows high transmittance of ∼87%–90%, an obvious photoelectric enhancement of ∼2.3 × 103 folds than that of ZnCo2O4/SrTiO3, and good stability in 6 months. The interfacial Tm:Bi2O3 QDs modification is deemed to be the core issue. In addition to Fermi level regulation and barrier transition for carrier transportation, the Tm:Bi2O3 QDs with high quantum yield can maintain high transparency and increase carrier injection for balancing transparency and power conversion efficiency (PCE), meanwhile achieving ultraviolet light conversion for wide bandgap semiconductor excitation via upconversion of Tm-doping, including Co2+/Co3+ induced hole, thereby promoting carrier dynamics transportation for high transparency-PCE.