The energy-down-shift effect of Cd0.5Zn0.5S-ZnS core-shell quantum dots on power-conversion-efficiency enhancement in silicon solar cells

We found that Cd0.5Zn0.5S-ZnS core (4.2 nm in diameter)-shell (1.2 nm in thickness) quantum dots (QDs) demonstrated a typical energy-down-shift (2.76-4.96 -> 2.81 eV), which absorb ultra-violet (UV) light (250-450 nm in wavelength) and emit blue visible tight (similar to 442 nm in wavelength). They showed the quantum yield of similar to 80% and their coating on the SiNx film textured p-type silicon solar-cells enhanced the external-quantum-efficiency (EQE) of similar to 30% at 300-450 nm in wavelength, thereby enhancing the short-circuit-current-density (J(SC)) of similar to 2.23 mA cm(-2) and the power-conversion-efficiency (PCE) of similar to 1.08% (relatively similar to 6.04% increase compared with the reference without QDs for p-type silicon solar-cells). In particular, the PCE peaked at a specific coating thickness of the Cd0.5Zn0.5S-ZnS core-shell QD layer; i.e., the 1.08% PCE enhancement at the 8.8 nm thick QD layer.This work was supported by the Brain Korea 21 PLUS Program in 2013 and IC Design Education Center (IDEC)