Semiconductor ferroelectric compositions and their use in photovoltaic devices
Disclosed herein are ferroelectric perovskites characterized as having a band gap, Egap, of less than 2.5 eV. Also disclosed are compounds comprising a solid solution of KNbO3 and BaNi1/2Nb1/2O3-delta, wherein delta is in the range of from 0 to about 1. The specification also discloses photovoltaic devices comprising one or more solar absorbing layers, wherein at least one of the solar absorbing layers comprises a semiconducting ferroelectric layer. Finally, this patent application provides solar cell, comprising: a heterojunction of n- and p-type semiconductors characterized as comprising an interface layer disposed between the n- and p-type semiconductors, the interface layer comprising a semiconducting ferroelectric absorber layer capable of enhancing light absorption and carrier separation.
1. A ferroelectric perovskite characterized as having a band gap, E gap , of less than 2.5 eV and comprising a solid solution of KNbO 3 and BaNi 1/2 Nb 1/2 O 3-δ , wherein δ is in the range of from 0 to about 1.
2. The ferroelectric perovskite of claim 1 wherein the band gap is less than about 2.0 eV.
3. The ferroelectric perovskite of claim 1 wherein the band gap is in the range of from about 1.1 eV to about 1.6 eV.
4. The ferroelectric perovskite of claim 1 , wherein the solid solution of KNbO 3 and BaNi 1/2 Nb 1/2 O 3-δ is represented as (1−x)KNbO 3-x BaNi 1/2 Nb 1/2 O 3-δ , wherein x is in the range of from about 0.01 to about 0.99.
5. The ferroelectric perovskite of claim 4 , wherein x is in the range of from about 0.1 to about 0.5.
6. The ferroelectric perovskite of claim 1 , wherein δ is in the range of from about 0.2 to about 0.3.
7. The ferroelectric perovskite of claim 1 , wherein the ferroelectric perovskite is ferroelectric up to at least 100 degrees C.
8. A photovoltaic device comprising the ferroelectric perovskite of claim 1 .