Electron and hole relaxation effect on power conversion efficiency of selective energy contacts solar cells

Selective energy contacts (SECs) are one of the best methods to realize high-efficiency solar cells. In this method, the generated hot electrons, due to absorption of short wavelengths before relaxation and making thermal loss such as conventional cases, are extracted and high electric potential is produced then output electric power is enhanced. We recently proposed this method and reported numerically calculated and simulated results, but it is assumed that the electron and hole relaxation time from upper energies were ignored and it is assumed that the relaxation time is larger than the extraction time of the electron and hole. In this work, electron and hole relaxation is modeled and the continuity equation is modified and then particle distribution differential equations in the layers of N and P are presented and solved. It is shown that the previously reported results are completely valid for a low scattering rate, and in a high-speed relaxation rate, the power conversion efficiency is reduced. Also, the quantum wells with small tunneling time can be used in the realization of the SECs and improve the power conversion efficiency. This study considers the effect of different parameters, especially electron and hole relaxation times, on the power conversion efficiency in SECs.