Wide temperature range, air stable, transparent, and self-powered photodetectors enabled by a hybrid film of graphene and single-walled carbon nanotubes

Transparent photovoltaic devices (TPVDs) have attracted increasing attention in emerging electronic devices. As the application scenarios extend, there raise higher requirements regarding the stability and operating temperature range of TPVDs. In this work, a unique preparation strategy is proposed for air stable TPVD with a wide operating temperature range, i.e., a nanoscale architecture termed as H-TPVD is constructed that integrates a free-standing and highly transparent conductive hybrid film of graphene and single-walled carbon nanotubes (G-SWNT TCF for short) with a metal oxide NiO/TiO₂ heterojunction. The preparation approach is suitable for scaling up. Thanks to the excellent transparent conductivity of the freestanding G-SWNT hybrid film and the ultrathin NiO/TiO₂ heterojunction (100 nm), H-TPVD selectively absorbs the ultraviolet (UV) band of sunlight and has a transparency of up to 71% in the visible light. The integrated nanoscale architecture manifests the significant hole-collecting capability of the G-SWNT hybrid film and the efficient carrier generation and separation within the ultrathin NiO/TiO₂ heterojunction, resulting in excellent performance of the H-TPVD with a specific detectivity of 2.7 × 10¹⁰ Jones. Especially, the freestanding G-SWNT TCF is a super stable and non-porous two-dimensional film that can insulate gas molecules, thereby protecting the surface properties of NiO/TiO₂ heterojunctions and enhancing the stability of H-TPVD. Having subjected to 20,000 cycles and storage in air for three months, the performance parameters such as photo-response signal, output power, and specific detectivity show no noticeable degradation. In particular, the as-fabricated self-powered H-TPVD can operate over a wide temperature range from −180 to 300 °C, and can carry out solar-blind UV optical communication in this range. In addition, the 4 × 4 array H-TPVD demonstrates clear optical imaging. These results make it possible for H-TPVD to expand its potential application scenarios.