Self-aligned carbon nanotubes yarns (CNY) with efficient optoelectronic interface for microyarn shaped 3D photovoltaic cells

An innovative solid state dye sensitized photovoltaic carbon nanotubes yarn (DSP-CNY) has been developed using thermally-stable and highly conductive carbon nanotubes (CNT) yarns (CNYs). These CNYs are highly inter-aligned, ultrastrong and flexible with excellent electrical conductivity, mechanical integrity and catalytic properties. The CNYs are coated with a dye-incorporated TiO₂ microfilm and intertwined with a second set of CNYs as a counter electrode (CE). The DSP-CNYs were developed without using any metal wires or any expensive transparent conductive oxides (TCOs), liquid electrolytes, or glass or plastic cladding. The maximum photon to current conversion efficiency (η_{AM 1.5}) achieved with prolonged-time stability was 2.57%. The yarn-shaped flexible cells were able to transport photocurrent over a significant distance using a simple cell configuration with a wide range of structural flexibility (30-330). These cells are capable of efficiently harvesting incident photons regardless of direction and generating photocurrents with high efficiency and long term stability.