Enhanced photovoltaic performance via polarization in Bi/Co co‐doped KN‐based ferroelectric ceramics

Abstract A bandgap‐tunable KNbO 3 ferroelectric ceramic was prepared by introducing Bi/Co ion. The existence of mixed valence states of Co 2+ /Co 3+ in the system induced the bandgap reduction and its tunable behavior. KNbO 3 –BiCoO 3 solid solutions showed a typical orthogonal perovskite structure and maintained good ferroelectricity ( P s = 15.13 µC/cm 2 ) and high‐field polarization ability. The devices based on the .98KNbO 3 –.02BiCoO 3 sample exhibited an improved short‐circuit photocurrent density ( J sc ) of 19.2 nA/cm 2 under simulated solar radiation, and this was further enhanced to 79.8 nA/cm 2 after a 60‐kV/cm polarizing. The structural analysis of the samples after polarization reveals the effect of ferroelectric polarization on photovoltaic performance. This work provides new insights into the effects of ferroelectric polarization on photovoltaic performance.