The energy-down-shift effect of Cd_(0.5)Zn_(0.5)S-ZnS core-shell quantum dots on power-conversion-efficiency enhancement in silicon solar cells

摘要

We found that Cd_(0.5)Zn_(0.5)S-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 light (~442 nm in wavelength). They showed the quantum yield of ~80% and their coating on the SiN_x film textured p-type silicon solar-cells enhanced the external-quantum-efficiency (EQE) of ~30% at 300-450 nm in wavelength, thereby enhancing the short-circuit-current-density (J_(SC)) of ~2.23 mA cm~(-2) and the power-conversion-efficiency (PCE) of ~1.08% (relatively ~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 Cd_(0.5)Zn_(0.5)S-ZnS core-shell QD layer; i.e., the 1.08% PCE enhancement at the 8.8 nm thick QD layer.