Multijunction photovoltaic fibers with record efficiency for energy-harvesting textiles

Abstract

Multijunction (MJ) photovoltaics offer the highest demonstrated solar power conversion efficiencies but have not been previously integrated into deformable textile architectures. Here, we demonstrate III–V MJ photovoltaic fibers (PVFs) that combine record PV performance with mechanical compliance and textile compatibility. Chip-scale III–V MJ PV dies are surface-mounted onto flexible fiber substrates using a scalable fabrication process compatible with textile integration. The resulting fibers achieve total-device-area power conversion efficiencies of 19.5% under AM1.5 illumination and 13.0% under AM0, representing the highest efficiencies reported to date for fiber-integrated PV devices. Based on a device coverage fraction along the fiber established by bending-fatigue constraints, a fully populated MJ PVF is projected to achieve a total fiber-area efficiency of 14.7% under AM1.5 illumination. Thermal cycling between −55 and +85 °C produces no measurable changes in PV performance metrics, indicating initial thermo-mechanical stability following integration. Using embroidery-based conductive interconnects, MJ PVFs are integrated into fabrics and shown to directly power light-emitting fibers, demonstrating energy-harvesting electronic textiles. These results establish MJ PVFs as a pathway toward lightweight, conformal PV systems for terrestrial and space applications.