Design and fabrication of bi-functional TiO₂/Al₂O₃ nanolaminates with selected light extraction and reliable moisture vapor barrier performance.

Bi-functional thin film with both selected light extraction and reliable moisture vapor barrier was proposed for simultaneous light management and encapsulation in the fields of lighting and display. Atomic layer deposition (ALD) was employed to obtain TiO2 and Al2O3 films with high uniformity, forming distributed Bragg reflector (DBR) structure. The DBRs exhibited excellent and tunable optical properties, as well as reliable moisture barrier performance. With increasing the DBR layers, the transmittances decreased obviously. The transmittance in the blue light region was as low as 0.66% for DBR with 6.5 pairs and the water vapor transmission rates (WVTR) value was 3.06×10-5 g/m2/day for DBR with 4.5 pairs. These DBRs were integrated in the red quantum dot (QD) based color converters excited by blue LED, enabling an obvious increase in red emission and a strong decrease in blue light transmittance. Furthermore, these DBRs can prolong the lifetime of QDs evidently by isolating the QDs from the moisture (oxygen) vapor. These results highlight the potentials for the exploitation of DBRs fabricated using ALD in the application of lighting and display devices based on QD photo-luminescence and electro- luminescence.