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Theoretical model and simulation of carrier heating with effects of nonequilibrium hot phonons in semiconductor photovoltaic devices
Author(s) -
Tsai ChinYi
Publication year - 2018
Publication title -
progress in photovoltaics: research and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.286
H-Index - 131
eISSN - 1099-159X
pISSN - 1062-7995
DOI - 10.1002/pip.3021
Subject(s) - phonon , charge carrier , relaxation (psychology) , photovoltaic system , materials science , non equilibrium thermodynamics , semiconductor , condensed matter physics , rate equation , carrier lifetime , optoelectronics , physics , thermodynamics , silicon , electrical engineering , classical mechanics , psychology , social psychology , engineering , kinetics
A theoretical model and its rate equations of carrier number and energy densities are proposed and presented for calculating carrier heating in semiconductor photovoltaic devices. The rate equation for carrier number density is the Shockley‐Queisser theoretical model, while the rate equation for carrier energy density includes the carrier interband energy relaxation via radiative recombination and the intraband energy relaxation via the interactions between carriers and polar longitudinal optical phonons. The carrier intraband energy relaxation is calculated by incorporating the effects of nonequilibrium hot phonons and the Thomas‐Fermi static screening. This model and its rate equations are employed for numerical simulations of the magnitude of carrier heating and its effects on the current‐voltage relations of bulk GaAs solar cells under different concentration ratios and with different widths of the active region. The simulation results demonstrate that carrier temperature in general heats up to 400 to 900 K at short‐circuit operating condition. This carrier heating cools down to lattice temperature when the device approaches its open‐circuit point. Based on these numerical results, effects of carrier heating on the performance of conventional solar cells and also their implications for the design of hot‐carrier solar cells will be discussed.