News Column

Shahid Beheshti university boosts solar cell efficiency

June 19, 2014

Science & Technology Desk

Researchers at Shahid Beheshti University produced copper chromium oxide (CuCrO2) nanoparticles, which improve the efficiency of p-type solar cells and reduce their cost.

Morteza Asemi and Majid Ghana'atshoar were researchers of the project.

CuCrO2 nanoparticles were synthesized by sol-gel method, which is a simple and cheap method.

The effect of annealing temperature, duration of heat treatment and metallic ion concentration in precursor solution on the structural properties of the nanoparticles was investigated.

It was found that the crystallite sizes as well as the size of nanoparticles increased with annealing temperature and duration of heat treatment but decreased with metallic ion concentration.

Nanoparticles' size was determined using particle size analyzer. They exhibit a large optical band gap that increases with metallic ion concentration.

To create a solar cell, the thin slices of silicon crystal must be modified. P-type and N-type silicon must be created by allowing a small concentration of another element to diffuse into the silicon crystal structure. P-type uses boron, 3 valence electrons and N-type uses phosphorus, 5 valence electrons.

The two types are created separately, thus there are no regions that have both boron and phosphorus within the silicon.

Wherever a boron atom exists, there is a vacancy in the crystal lattice because it can only bond to neighboring silicon atoms in three places. Conversely, the phosphorus-doped silicon has extra free electrons floating around each phosphorus nucleus. Solar cells are arranged with alternating sections of p-type and n-type silicon.

P-type solar cells have attracted interest due to the potential applications in tandem devices as well as in the artificial photosynthesis systems.

CuCrO2 nanoparticles also have applications in electrochemical cells and opto-electronic industry.

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Source: Iran Daily

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