How does the negative hydrogen ion make the Sun’s photosphere opaque?

The negative hydrogen ion ($H^{-}$), which consists of a hydrogen nucleus with two electrons attached, is the primary reason the Sun’s photosphere is opaque.

While the density of the ionized gas in the photosphere is quite low—about 1/1,000 that of air at Earth’s surface—the $H^{-}$ ion absorbs radiation voraciously across most of the visible spectrum. This strong absorption prevents photons generated deeper within the Sun from escaping directly, effectively creating the visible "surface" that we observe as the photosphere.12