Ideal efficiency = (1/q * E_g * I_inc) / P_in. For AM1.5, its maximum is 48% at 1.1 eV bandgap energy.
Shockley–Queisser limit is 31% for a black body and AM0 spectrum. May you explain the difference further?
S-Q takes into account unavoidable radiative losses of energy. This leads to slightly lower current, because some electron-hole pairs recombine radiatively, and lower voltage, because the the maximum voltage is given by the quasi-Fermi level splitting which, while it can't exceed Eg, never reaches Eg either. For more details I'd suggest you read their paper.
S-Q takes into account unavoidable radiative losses of energy. This leads to slightly lower current, because some electron-hole pairs recombine radiatively, and lower voltage, because the the maximum voltage is given by the quasi-Fermi level splitting which, while it can't exceed Eg, never reaches Eg either. For more details I'd suggest you read their paper.
To calculate the the ultimate efficiency (ideal efficiency) it is assumed that: 1) each absorbed photon (with hv >Eg) will create an electron-hole pair, 2) at the contacts each collected pair will transmit energy equal to Eg. This will result in 48% efficiency.
To calculate the SQ efficiency limit two other limiting factors(intrinsic) are added: 1) the absorbed photons from solar radiation are either collected by an external load or recombine (radiative recombination is the only allowed mechanism in order to attain maximum efficiency) 2) due to thermodynamical considerations (entropy) the maximum energy delivered by each electron-hole pair collected at contacts cannot exceed the difference between their quasi-Fermi levels, which is always less than Eg.
- Badges
- Science topic