Piezo-photovoltaic coupling in CdS-based thin-film photovoltaics

We report a summary of our recent study of piezo- and pyroelectricity in CdS-based photovoltaics including CdTe and CuIn(Ga)Se-2 absorber devices. The strong pyro- and piezo-effects in CdS significantly affect the electric field distribution and the physics of device operations. We introduce the concept of pyro-photovoltaic coupling where the photovoltaic effect and the CdS polarization strongly depend on each other. Our quantitative modeling shows that the CdS polarization turns out to be beneficial for photovoltaic technology, making it more forgiving. Three experimental setups utilized in our work were aimed at exerting mechanical stresses corresponding to the device squeezing, bending, and flexing; we used the substrate, superstrate, and flexible substrate structures. Our understanding points at previously unexplored venues in thin-film photovoltaic technology. (c) 2007 American Institute of Physics.