Engineering of optically defect free Cu_2O enabling exciton luminescence at room temperature

Cu2O is an interesting semiconductor with extraordinary high exciton binding energy, however exhibiting weak room temperature excitonic luminescence. The issue was addressed in literature emphasizing a detrimental role of native point defects responsible for optical quenching. Resolving the problem, we propose a method to manipulate the Cu and O vacancies contents opening a gateway for optoelectronic applications of Cu2O. Specifically, applying oxygen lean conditions, we observe a remarkable suppression of VCu enabling strong room temperature exciton luminescence, while manipulating with VO reveals no impact on the signal. As a result, the excitonic signature was interpreted in terms of phonon assisted transitions.