| Abstract: | We study the formation of trions - bound states of excitons and holes (or electrons), in quasi-1D semiconducting systems. We argue that trions can form spontaneously in the vicinity of a phase transition between a band insulator and an excitonic insulator upon doping, giving rise to a trion liquid. We employ the density-matrix renormalization group (DMRG) method to study the aforementioned phase transition in a one-dimensional model motivated by Ta2NiS5, and identify a regime in parameter space in which a trion liquid forms upon hole doping. We study the spectral signatures of trions as could be probed using angle-resolved photoemission (ARPES) both in the undoped and doped regimes. |