Resonant tunneling diodes as energy-selective contacts used in hot-carrier solar cells

Abstract

Among the four features unique to hot-carrier solar cells (HC-SCs): (i) carrier thermalization time and (ii) carrier equilibration time in the absorber, (iii) energy-selection width and (iv) conductance of the energy-selective contacts (ESCs), requisites of (i)-(iii) for high conversion efficiency have been clarified. We have tackled the remaining issues related to (iv) in the present study. The detailed balance model of HC-SC operation has been improved to involve a finite value of the ESC conductance to find the required values, which in turn has been revealed to be feasible using resonant tunneling diodes (RTDs) consisting of semiconductor quantum dots (QDs) and quantum wells (QWs) by means of a formulation to calculate the conductance of the QD- and QW-RTDs derived using the rigorous solutions of the effective-mass Hamiltonians. Thus, all of the four requisites unique to HC-SCs to achieve high conversion efficiency have been elucidated, and the two requisites related to the ESCs can be fulfilled using the QD- and QW-RTDs.

The effects of intraband and interband carrier‐carrier scattering on hot‐carrier solar cells: A theoretical study of spectral hole burning, electron‐hole energy transfer, Auger recombination, and impact ionization generation

“…On the contrary, hot‐carrier solar cells are designed and constructed to convert the heat power p heat into useful electrical power. In the RN model, the ideal hot‐carrier solar cells are established with two essential components: one is energy‐selective contacts in which carriers are extracted through a specific energy window, and the other is isentropic processes (ie, the balance of carrier entropy flux) at these contacts . Ideal energy‐selective contacts are assumed in the RN model in which the extraction energy E ext of an electron‐hole pair is the same as the energy difference between energy‐selective windows for electrons and holes ΔE sc : …”

“…It should be particularly reminded here that the above discussion is limited to cases with ideal energy‐selective contacts of a single selective energy. However, realistic energy‐selective contacts have energy windows where carriers can be extracted through a finite range of energies, rather than a specific energy . Under such a circumstance, the energy spectrum of a spectral hole needs a convolution with the energy window of the selective contacts.…”

“…However, realistic energy-selective contacts have energy windows where carriers can be extracted through a finite range of energies, rather than a specific energy. [59][60][61][62][63][64][65][66][67] Under such a circumstance, the energy spectrum of a spectral hole needs a convolution with the energy window of the selective contacts. Therefore, it can be expected that larger selective energy windows will make the spectral hole broader.…”

Nonequilibrium Theory of the Conversion Efficiency Limit of Solar Cells Including Thermalization and Extraction of Carriers

“…The reduction of η max in fast extraction regime III in Fig. 10 may be confusing because the hot carrier solar cells that are targeted in this regime can surpass the SQ limit of η SQ theoretically [3][4][5][6][7] . Therefore, we may expect an increase in η max as τ out decreases in regime III.…”

Electron extraction from excited quantum dots with higher order coulomb scattering

“…In order to efficiently employ these hot-carrier schemes energetically narrow filters must be implemented which allow for selective extraction of excitons [14,[35][36][37]. The hot-carrier solar cell thus requires an appropriate kinetics and properly matched extraction processes, which we study in detail in this article.…”