N-Type Colloidal-Quantum-Dot Solids for Photovoltaics

N-type PbS colloidal-quantum-dot (CQD) films are fabricated using a controlled halide chemical treatment, applied in an inert processing ambient environment. The new materials exhibit a mobility of 0.1 cm(2) V-1 s(-1). The halogen ions serve both as a passivating agent and n-dope the films via substitution at surface chalcogen sites. The majority electron concentration across the range 1016 to 10(18) cm(-3) is varied systematically.