Achieving Ultrahigh Photocurrent Density of Mg/Mn-Modified KNbO3Ferroelectric Semiconductors by Bandgap Engineering and Polarization Maintenance

Yuchen Lan, Wenbin Tang, Changlai Yuan, Jian Xiong, Xiaogang Xue, Jun Chen, Lei Miao, Jingtai Zhao, Guang Hui Rao, Yiping Guo, Changrong Zhou, Biaolin Peng

研究成果: Article査読

2 被引用数 (Scopus)

抄録

Most traditional oxide ferroelectric ceramics produced a low photocurrent density in the order of ∼nA/cm2, which greatly limits their application in photovoltaic devices. In this study, a novel solid solution of Mg/Mn-modified KNbO3 (i.e., (1 - x)KNbO3-xMgMnO3-δ, x = 0.00-0.08) ferroelectric semiconductors was synthesized using the solid-phase method. An ultrahigh short-circuit current density (Jsc) of 15.8 μA/cm2 was achieved in the 0.94KN-0.06MM ceramic under 1 sun illumination (AM1.5G, 100 mW/cm2), which is two orders of magnitude higher than that of typical (KNbO3)1-x(BaNi1/2Nb1/2O3-δ)x ferroelectric semiconductors. After high-field poling, a further enhanced Jsc (40 μA/cm2) was obtained in the 0.94KNbO3-0.06MgMnO3-δ ceramic, which is 2.5 times higher than that of the unpoled sample. Moreover, a large open-circuit voltage (Voc) of 16.5 V and a high Jsc of 13.8 μA/cm2 were successfully achieved in the 0.94KN-0.06MM ceramic under visible light (λ > 420 nm) illumination. The high Jsc in the modified system was induced by a combination of low optical bandgaps of 2.60-1.00 eV and a perfectly ferroelectric internal built-in field. On the basis of density functional theory calculations, the bandgap reduction in ceramics was mainly attributed to the introduction of the spin-up Mn 3dxz state in the valence band maximum and spin-up Mn 3dz2 state in the conduction band minimum. The conduction species from the grains and grain boundaries of the 0.94KN-0.06MM ceramic were mainly composed of doubly ionized oxygen vacancies induced by the introduction of Mn3+. These findings provide a new view for developing novel oxide ferroelectric photovoltaic materials with high photocurrent density.

本文言語English
ジャーナルChemistry of Materials
DOI
出版ステータスAccepted/In press - 2021

ASJC Scopus subject areas

  • 化学 (全般)
  • 化学工学(全般)
  • 材料化学

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