Pressure-tuned multiferroic KBiFe2O5 - Dr. Ganghua Zhang
MARCH 16, 2017
New study from a team of HPSTAR scientists, led by Drs. Ganghua Zhang and Wenge Yang, find that pressure can simultaneously enhance ferroelectric and photoelectric properties of multiferroic KBiFe2O5. These findings may open a new avenue to discovering and designing optimal ferroelectric compounds for solar energy applications. The work was highlighted on the Advanced Electronic Materials cover.
Multiferroic materials are highly promising for solar applications, and also potentially useful in devices like electronic sensors and flash memory drives because of absorbing solar radiation and possessing unique electrical and magnetic properties.
“Scientists have put a lot of efforts to improve the light absorption, optoelectronic properties of multiterroics from several ways,” said Dr. Ganghua Zhang, who led the research while he was a postdoc fellow in Dr. Wenge Yang’s group.
“We know that pressure is very significant technique in tuning physical properties of energy materials, eg. 2D materials, solar perovskites etc.” added Ganghua. “So we are expecting how pressure will change ferroelectric photovoltaics’ performance.”
The team utilized multiple high-pressure techniques and theoretical calculations to probe the crystal structure, bandgap, ferroelectric and optoelectronic properties of the multiferroic KBiFe2O5 — a new multiferroics with optimal properties for solar applications.
Above about 7 gigapascals, the scientists observed a new phase with four times polarizations of the ambient phase. “This definitely means pressure enhanced ferroelectric polarization of KBiFe2O5,” said Dr. Wenge Yang, a staff scientist of HPSTAR and a senior author of the paper.
“The pressure–induced polarized new phase is promising ferroelectric photovoltaic material and great candidate for photosensitive switch applications,” added Dr. Wenge Yang.
This pressure induced phase transition also enhanced the electron transport, and visible light response in KBiFe2O5.
This study suggest that the hydrostatic pressure techniques have great potential as versatile tools to tune the structural, ferroelectric and optoelectronic properties of the ferroelectric materials toward better photovoltaic performances.
The other authors of the study are Fengliang Liu, Tingting Gu, Yongsheng Zhao, Nana Li of HPSTAR and Shouhua Feng of Jilin University.
对新型窄带隙铁电材料的探索和现有铁电材料光伏性能的优化研究已有很多途径和方法，但铁电材料光伏效率依然很低，这主要是由于缺乏有效手段来同时优化铁电材料的铁电性与导电性。研究表明：更大的剩余极化强度产生更高的光生电流和光电转换效率。然而，铁电材料的电阻率都较高、导电性较差，这就导致材料的载流子浓度和迁移率都很低，是阻碍铁电材料光电转换效率进一步提升的根本因素。北京高压科学研究中心张刚华博士带领的团队利用高压技术结合理论计算探究了一种新型铁电光伏材料KBiFe2O5在压力条件下晶体结构、禁带宽度、铁电性能及光电性能的演变行为。他们发现通过高压诱导微结构相变的手段可以同时增强铁电材料KBiFe2O5的铁电性能和光伏性能。此研究为设计和开发具有高性能的铁电光伏材料提供了一条简单有效的新途径。