Light-emitting diode A light-emitting diode (LED) is a semiconductor device that emits light when an electric current passes through it \usepackage{color,graphicx,circuitikz} \begin{document} \begin{circuitikz}[american, thick] \draw (0,0) to [leDo, l={$$}](2,0); \end{circuitikz} \end{document}