Aspects of sintering CdTe nanoparticles into functional bulk absorber layers

Sintering semiconductor nanocrystals represents a possible low-cost route to creating functional bulk absorber layers for photovoltaic applications. Here we highlight the critical aspects of sintering CdTe tetrapods into smooth, dense, polycrystalline films that are capable of yielding >7% efficient solar cells with just ~500 nm thick active layers. Despite respectable performance, we find that there is room for improvement regarding the current state-of-the-art processing and device structure. Namely, `optimal' films/devices have exceptionally low photoluminescence yield, grain sizes on the order of 50-100 nm, a metastable ITO/CdTe hole-collecting contact, and CdTe that is not phase pure. Our findings further suggest that this approach to creating functional CdTe absorber layers has great potential beyond the already encouraging results reported in the literature.