A stretchable light electrochemical cell based on CsPbBr3 and a distributed GaP nanowire array with a single-walled carbon nanotube electrode

Abstract

Flexible electronics aim to provide stretchable light-emitting devices for daily life capable of withstanding multiple stretch–relaxation cycles. In this paper, we present a stretchable green perovskite light electrochemical cell (PeLEC) with a CsPbBr₃ active layer, where a vertically oriented GaP nanowire (NW) array combined with a pre-stretched uniaxial electrode based on single-walled carbon nanotubes (SWCNT) is used as a distributed stretch-resistant electrode. To achieve PeLEC stability, the array of NWs is embedded 1.5–2 µm deep into the perovskite layer, while the total perovskite layer thickness is 2–3 µm. Stretch-related electroluminescence (EL) measurements demonstrate a stable emission peak at 535 nm for initial and stretched device states with a threshold voltage of 8.5 V. The slight difference in the observed EL intensity after stretching can be explained by the changes in the CsPbBr₃ film geometry, such as the increase of the space between perovskite crystals under uniaxial strain, which reduces the effective emissive volume within the device area, and by the partial restructuring of the SWCNT network. The impedance spectroscopy tests of the CsPbBr₃ device show that although the lateral resistance increased by 7 times after more than 100 stretch–relaxation cycles (primarily due to cracking of the perovskite crystals), the operation current of the stretchable PeLEC does not significantly change. This mechanical stability is attributed to the GaP NW-based distributed electrode architecture, which efficiently accommodates perovskite crystal cracking. These results demonstrate the potential of the proposed stretchable PeLEC architecture for flexible and stretchable electronics.