Sub-¹/₁₀ exciton threshold lasers using stable self-charged perovskite quantum rods

Colloidal quantum dots (QDs) are promising optical gain materials that require a reduction in the threshold to reach their full potential. While QD charging theoretically reduces the threshold to zero, its effectiveness has been limited by strong Auger recombination and unstable charging. In this study, we theoretically determine the optimal combination of charging number and Auger recombination to minimize the lasing threshold. Experimentally, we develop stable, self-charged perovskite quantum rods (QRs) as an alternative to QDs via the state engineering and Mn (manganese) doping strategy. A two-order-of-magnitude reduction in nonradiative Auger recombination enables QRs to support a charging number of up to 6. We then achieve QR liquid lasing with a sub-¹/₁₀ exciton threshold (an average of 0.098 excitons per QR) using 5-nanosecond pulse pumping. This threshold is exceptionally low among all reported QD lasers. These achievements demonstrate the potential of specially engineered QRs as excellent gain media and pave the way for their applications.