Micro-transfer printing high-efficiency GaAs photovoltaic cells onto silicon for wireless power applications

TL;DR

This paper reports the development and transfer printing of high-efficiency GaAs laser power converters onto silicon, enabling scalable, low-cost wireless power solutions for implantable and IoT devices.

Contribution

It introduces a novel transfer printing method for GaAs photovoltaic cells onto silicon, achieving high efficiency and current density for wireless power applications.

Findings

Achieved 48-49% optical power conversion efficiency.

Successfully transferred 300 μm GaAs devices onto silicon.

Demonstrated high current densities up to 70 A/cm2.

Abstract

Here we report the development of high-efficiency microscale GaAs laser power converters, and their successful transfer printing onto silicon substrates, presenting a unique, high power, low-cost and integrated power supply solution for implantable electronics, autonomous systems and internet of things applications. We present 300 {\mu}m diameter single-junction GaAs laser power converters and successfully demonstrate the transfer printing of these devices to silicon using a PDMS stamp, achieving optical power conversion efficiencies of 48% and 49% under 35 and 71 W/cm2 808 nm laser illumination respectively. The transferred devices are coated with ITO to increase current spreading and are shown to be capable of handling very high short-circuit current densities up to 70 A/cm2 under 141 W/cm2 illumination intensity (~1400 Suns), while their open circuit voltage reaches 1235 mV, exceeding the values of pre-transfer devices indicating the presence of photon-recycling. These optical power sources could deliver Watts of power to sensors and systems in locations where wired power is not an option, while using a massively parallel, scalable, and low-cost fabrication method for the integration of dissimilar materials and devices.