Next generation photovoltaic research seeks to shift the current state of energy production. By developing solar cells that are both highly efficient and low-cost, energy production can be transformed from relying on fossil fuels to using renewable sources. One route toward reaching high efficiency photovoltaic devices is through the use of nanocrystalline (NC) material. In particular, NCs are useful in photovoltaic devices as light sensitizers, as electron or hole conductors within composite films, as an absorber layer that acts to both absorb light and transport charge within a quantum-confined yet electronically coupled array, or simply as an ink to provide a new route toward bulk materials (here termed ink-based solar cells). We present the use of cadmium telluride (CdTe) nanocrystal colloids deposited by a layer-by-layer process into thin film devices. The initial nanocrystal size, crystal structure, and crystal habit influence the resulting grain structure and solar cell performance. Inks composed of predominantly wurtzite tetrapod-shaped nanocrystals exhibit better device performance compared to inks composed of irregular faceted nanocrystals or spherical zincblende nanocrystals, despite the final sintered film converting to the zincblende crystal structure. Investigating the effects of various chemical treatments on five distinctive solar cell architectures yields the surprising result that an indium tin oxide/CdTe/zinc oxide structure leads to our best performing device. An efficiency &gt;11% compared to others, including two with a cadmium sulfide (CdS) n-type layer typically used in high efficiency sublimation-grown CdTe solar cells, indicates that ink-based CdTe solar cells operate differently than traditional vapor-deposited CdTe solar cells.

Understanding the role of chemical treatments and device architecture on ink-based CdTe solar cells

249th National Meeting (2015)

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