11.3% CdS ferroelectric-semiconductor coupling solar cell

Ferroelectric-semiconductor coupling solar cell is a novel concept of photovoltaic device, with nano piezoelectric particles embedded in light-absorbing semiconductors. In this work, we successfully realized such devices with S-rich CdSTe nano particles of hexagonal phase with wurtzite structure embedded in Te-rich CdSTe film of cubic phase with zinc blend structure through a high temperature phase segregation process. TEM analysis confirms phase segregation and formation of S-rich CdSTe particles in a size of 100nm, which distribute uniformly in the Te-rich CdSTe bulk layer. This photovoltaic mechanism has been proved by other microscopic and macroscopic evidences, which are presented in this report. More interestingly, tenability of conversion efficiencies, especially open circuit voltages, in such devices has been realized both after and during the fabrication process. By applying an external bias across the film during the formation of the ferroelectric particles, a linear relationship between Voc and the field strength has been observed. Meanwhile, such cells exhibit performance improvement over time in months after storage with encapsulation in ambient environment. The best conversion efficiency of CdS ferroelectric-semiconductor coupling solar cell has reached 11.3% by such in situ polarization technique.