A black silhouette of a light bulb mostly based on openclipart.org/detail/155965/light-bulb-minimal-design. I also used openclipart.org/detail/104485/ampoule-light-bulb for the inner part. The background is completely transparent.
燈泡剪影
B&W Icons、Black、Bulb、Design、electric light、icons、icons - 1 family、idea、Light、light、Minimal、pictogram、remix 104485、remix 155965、silhouette
B＆W圖標、黑色、燈泡、設計、電燈、圖標、圖標 - 1個家庭、理念、光、光、最小、圖標、混音104485、混音155965、輪廓
資料來源：openclipart ( https://openclipart.org/ )