To improve the energy-conversion efficiency of betavoltaic cells, we design an energy-conversion unit that couples zinc oxide (ZnO) nanorod arrays (ZNRAs) with cuprous-oxide (Cu 2 O) quantum dots (QDs) and evaluate it under a Formula: see textNi source. Monte Carlo particle transport, combined with carrier-transport theory, is used to elucidate how material choices, structural parameters and device geometry govern beta (Formula: see text-particle energy collection, conversion and electrical output. For the ZNRAs-Cu 2 O architecture, a QD layer thickness of 200Formula: see textnm maximizes the Formula: see text-particle energy-transfer depth (Formula: see text1300Formula: see textnm), while a 25Formula: see textnm nanorod spacing provides a practical structural optimization threshold. Owing to its high molecular number density (Formula: see textFormula: see textcmFormula: see text), ZnO acts as the principal energy-deposition region (total energy loss Formula: see text5670Formula: see texteV). Although the Cu 2 O QDs have a lower molecular number density (Formula: see textFormula: see textcmFormula: see text) and a small thickness, they enhance carrier separation through quantum confinement and heterojunction synergy; the built-in field at the Cu 2 O/ZnO interface promotes drift transport. In the optimized structure, reduced defect impact extends carrier lifetime and improves collection efficiency, yielding a short-circuit current density of 0.0287Formula: see textmA cmFormula: see text and an open-circuit voltage of 0.447 V. These results reveal the synergistic-gain mechanism across the chain of “energy depositionFormula: see textcarrier transportFormula: see textelectrical conversion,“ providing a quantitative basis for analyzing and optimizing betavoltaic devices.
Liu et al. (Fri,) studied this question.