  Simultaneous wireless information and power transfer (SWIPT) is an effective
energy-saving technology, but its efficiency is hindered by environmental
factors. The introduction of reconfigurable intelligent surfaces (RIS) has
alleviated this issue, although it still faces significant constraints due to
geographical limitations. This paper proposes a scheme that employs a
simultaneously transmitting and reflecting (STAR)-RIS to assist SWIPT. It can
overcome this limitation, achieve higher degrees of freedom (DoF), and provide
better quality of service (QoS) for users on both sides of the ground.
Meanwhile, we have considered a hybrid device based on a power splitting, which
is capable of both energy harvesting and information decoding. We have proposed
an efficient alternating optimization (AO) method to optimize the phase and
amplitude vectors for reflection and transmission, beamforming and the optimal
power splitting ratio, achieving an optimal balance between data rate and
energy efficiency. Finally, simulation results demonstrate that the sum rate of
the proposed model is superior to traditional RIS and other benchmark schemes.
