KVPY 2020-21 SB SX Exam Previous Papers

Question : 99 of 120

Marks: +1, -0

A solar cell is to be fabricated for efficient conversion of solar radiation to emf using material A. The solar cell is to be mechanically protected with the help of a coating using material B. If the band gap energy of materials

{A}

and

{B}

are

{E}_{{A}}

and

{E}_{{B}}

respectively, then which of the following choices is optimum for better performance of the solar cell.

${E}_{{A}}=1.5 {eV}, {E}_{{B}}=5 {eV}$
${E}_{{A}}=1.5 {eV}, {E}_{{B}}=1.5 {eV}$
${E}_{{A}}=3 {eV}, {E}_{{B}}=1.5 {eV}$
${E}_{{A}}=0.5 {eV}, {E}_{{B}}=5 {eV}$

Validate

Solution:

Generally we want the electron to cross energy gaps in material A.
Not in material-B because its just covering.
And

E_g

in the A should not be very small otherwise there will be huge heat loss because of large difference in

E_g

and energy of incident photon

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