Electrical and optical properties of Si microwire solar cells

- Various geometries were given for Si microwire (SiMW) solar cells.
- The effect of minority carrier lifetime was investigated.
- Depletion width and recombination probability is a function of geometry.
- Diameter design is pivotal to collect carriers for enhanced performance.

A record-high efficiency of 16.92% was realized by using microscale-patterned Si solar cells. Si microwire (SiMW) solar cells were designed to compare their performances with the standard flat-Si solar cell. The diameter and period of SiMWs were tuned to investigate the effects on the operation and the electrical properties of the solar cells. The highest efficiency SiMW solar cell has a width of 1.57 µm to provide the significantly enhanced efficiency of 16.92% from 10.15% of the flat-Si solar cell, due to the improved values of open circuit voltage (608 mV), short circuit current density (36.47 mA/cm2) and fill factor (76.29%). Impedance spectroscopy and capacitance-voltage studies were carried out to obtain series and shunt resistances, built-in potential, acceptor carrier density, depletion width and flat band potential. Optical properties of SiMW solar cells were analyzed by external and internal quantum efficiencies. The carrier lifetime was measured by using open circuit voltage decay technique. Systematic analyses were performed to reveal the optical and electrical features of SiMW solar cells. These findings may provide efficient design schemes for high-performing solar cells using structured platforms.