High-Efficiency Ferroelectric-Film Solar Cells with an n-type Cu₂O Cathode Buffer Layer

Abstract

Because of the existence of interface Schottky barriers and depolarization electric field, ferroelectric films sandwiched between top and bottom electrodes are strongly expected to be used as a new kind of solar cells. However, the photocurrent with a typical order of μA/cm(2) is too low to be practical. Here we demonstrate that the insertion of an n-type cuprous oxide (Cu(2)O) layer between the Pb(Zr,Ti)O(3) (PZT) film and the cathode Pt contact in a ITO/PZT/Pt cell leads to the short-circuit photocurrent increasing 120-fold to 4.80 mA/cm(2) and power conversion efficiency increasing of 72-fold to 0.57% under AM1.5G (100 mW/cm(2)) illumination. Ultraviolet photoemission spectroscopy and dark J-V characteristic show an ohmic contact on Pt/Cu(2)O, an n(+)-n heterojunction on Cu(2)O/PZT and a Schottky barrier on PZT/ITO, which provide a favorable energy level alignment for efficient electron-extraction on the cathode. Our work opens up a promising new method that has the potential for fulfilling cost-effective ferroelectric-film photovoltaic.

Interface band structure engineering by ferroelectric polarization in perovskite solar cells

“…Photovoltaic effect has been reported in many ferroelectric materials (such as BiFeO 3 , Pb(Zr,Ti)O 3 , and Bi 2 FeCrO 6 ) with best efficiency of 8.1% for ferroelectric solar cells based on Bi 2 FeCrO 6 [20][21][22][23][24][25][26][27][28][29]. These ferroelectric solar cells have been proposed to utilize the polarization electric field to drive the charge separation and transport.…”

Applications of ferroelectrics in photovoltaic devices

“…Many ferroelectric materials with relatively high Curie temperature have been demonstrated; these materials can be used in solar cells because they can retain their ferroelectric properties even at practically high temperatures associated with the operation of solar cells. Significant research has been performed on the photovoltaic characteristics of BTO [20,21], lead zirconate titanate (PbZrxTi1−xO3, PZT) [22][23][24], bismuth titanate (Bi4Ti3O12) [25], potassium sodium niobate (K0.5Na0.5NbO3, KNN) [26,27], and BFO [21,28,29].…”

“…In light of the above-mentioned limitations, the conversion efficiency of conventional simple MFM and MSM structures cannot meet the requirements imposed by practical applications. For a simple ITO/PZT/Pt structure, the device consists of two back-to-back Schottky diodes, and the work function of the Pt electrode is high (5.6 eV) so that most of the electronics cannot cross into the interface Schottky barrier of the Pt electrode, and it is difficult to increase the current [22]. When studying the photovoltaic effect in ITO/ZnO/BFO/Pt heterostructures, Fan et al [67] discovered that the ZnO/BFO interface can form an n + -n junction.…”

Applications of Oxide Coatings in Photovoltaic Devices

“…Recently, more studies have shown that the value of the above-band gap photovoltage of ferroelectric BiFeO 3 can be tuned by varying the number of nanometre scale domain walls with alternating polarity, and additionally, by varying the applied electrical field [183]. However, the efficiency of such devices based on ferroelectric materials such as BiFeO 3 and Pb(Zr,Ti)O 3 (PZT) remains very low due to the low fill factor and Jsc [184][185][186] PV cells using KNbO 3 , another perovskite ferroelectric material, as the absorber have been reported [53].…”