The US Department of Energy's National Renewable Energy Laboratory (NREL) has confirmed Longi's achievement of a world record-breaking efficiency rating of 33.9% for a perovskite-silicon tandem solar cell.
The materials that do the absorption are not effective across the entire wavelength spectrum of the sun. They can only absorb at a certain wavelength range, but the spectrum range of the sun is very wide.
Edit. Also other reasons, like recombination rate where the photon hitting the panel generates an electron-hole pair which is then collected and used for evegy, but electrons and holes tend to want to recombine, after which we cannot use them for evergy. We want this rate to be zero, but it never is, it is a probabilistic process. So even if you can absorb everything, you can’t utilise everything you absorb.
The materials that do the absorption are not effective across the entire wavelength spectrum of the sun. They can only absorb at a certain wavelength range, but the spectrum range of the sun is very wide.
Edit. Also other reasons, like recombination rate where the photon hitting the panel generates an electron-hole pair which is then collected and used for evegy, but electrons and holes tend to want to recombine, after which we cannot use them for evergy. We want this rate to be zero, but it never is, it is a probabilistic process. So even if you can absorb everything, you can’t utilise everything you absorb.