Contrasting properties of free carriers in $n$- and $p$-type Sb${}_2$Se${}_3$

We report persistent photoconductivity in $p$-type Sb${}_2$Se${}_3$ single crystals doped with Cd or Zn, where enhanced conductivity remains for hours after illumination ceases at temperatures below $\sim$25~K. Comparative transport and infrared absorption measurements, including on $n$-type Cl-doped counterparts, reveal strong indications that hole transport in Sb${}_2$Se${}_3$ is more strongly affected by intrinsic carrier scattering than electron transport. These results point to a fundamental asymmetry in charge carrier dynamics and highlight the potential role of polaronic effects in limiting hole mobility in this quasi-one-dimensional semiconductor.