(26a) Low-Temperature Approaches to Inorganic Photovoltaic Thin Films

Solution-based precursors are promising route to synthesizing thin film photovoltaic semiconductors which can be printed using low cost, high-throughput techniques such as roll-to-roll processing. A major limitation is the processing of these precursors to semiconductors; in order to achieve electronic and optoelectronic properties which are suitable for application in photovoltaics, high temperatures and harsh processing atmospheres are often required, which limits the benefits of solution-based precursors. In this presentation, we discuss some low-temperature approaches to synthesizing thin films at low temperature with excellent electronic properties. For example, we find that metastable wurtzite CdTe tetrapods undergo a phase transformation at 350°C and undergo sintering to produce grain sizes of several hundred nanometers. Additionally, thin films passivated with compositionally-matched chalcogenidomettalate clusters can have electron carrier mobilities in excess of 200 cm² V^-1 s^-1. When integrated into photovoltaic devices, we find that the power conversion efficiencies greater than 12% along with evidence that much higher efficiencies could be achieved with optimization of contact layers.