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Hot Carrier Approach to the Efficiency of a Solar Cell
S. Ašmontas, J. Gradauskas, A. Sužiedelis, A. Šilenas, E. Širmulis, V. Švedas, V. Vaicikauskas, O. Žalys
New Materials and Concepts for Photovoltaic Devices
Subtopic: Fundamental Studies
Event: 36th European Photovoltaic Solar Energy Conference and Exhibition
Session: 1BV.3.2
ISBN: 3-936338-60-4
0,00 EUR
Document(s): poster


Efficiency of a single-junction solar cell is limited by the Shockley-Queisser theory which assumes that only photons having energy close to a semiconductor forbidden energy gap are used effectively (Fig. 1; act 1). The residual extra energy of the high energy photons is reckoned in only through the process of carrier thermalization, i.e. through the lattice heating, while the low energy photons are assumed to be not absorbed at all. Hot carriers are free carriers with energy higher than the average one. One way of carrier heating can be realized by the light photons having energy lower than a semiconductor forbidden energy gap. Such intraband light absorption leads to rise of hot carrier photoemf across a semiconductor p-n junction (Fig. 1; act 2). This process has been investigated in Ge [1,2], Si [3], GaAs [4] and InSb [5] p-n junctions. Another possible way of carrier heating can be implemented by use of residual photon energy left over during the electron-hole pair generation due to the absorption of high energy photons.