Solution processing of CdTe nanocrystals for thin-film solar cells

We describe solution-processed sintered nanocrystal solar cells. As the absorber layer, thin-films of CdTe nanocrystals were deposited using a layer-by-layer spin coating process. For Schottky barrier solar cells (ITO/CdTe/Ca/Al), an efficiency of 3.0±0.3% with V_oc= 0.53±0.03 V, J_sc= 13.2±0.2 mA/cm², and FF=43.1±4.2% was measured under AM1.5G conditions. In order to overcome the limitations associated with the Schottky barrier structure, heterojunction solar cells incorporating solution-processed CdSe nanocrystals as an n-type layer were fabricated and characterized. Under darkness, heterojunction devices (ITO/CdTe/CdSe/Al) showed an improved current rectification ratio of 4.53×10² at ±1V in comparison to Schottky barrier solar cells, indicating that a well-defined junction is formed between CdSe and CdTe. Under illumination (AM1.5G), the devices exhibited an average efficiency of ~2% with V_oc=0.50±0.02 V.