Optimisation of alumina coating by atomic layer deposition (ALD) process as a protective scheme for CsPbBr3 perovskite quantum dots

Abstract

All-inorganic perovskite quantum dots (PeQDs) have emerged as a new class of semiconductor nanocrystals with outstanding optical characteristics. Two main practical problems have to be addressed before implementing PeQDs in energy harvesting architectures: anion-exchange and stability under various stringent conditions. Nanocomposites of QD/AlOx assembled using an atomic layer deposition (ALD) process has been developed in the recent years for the growth of amorphous alumina (AlOx) as a new protection technique for these semiconductor nanocrystals, that acts as a gas and ion diffusion barrier. This thesis work has optimized the ALD process using different ALD modes of operation. Each deposition cycle of the optimized ALD process comprised of a TMA pulse (t1), diffusion (t2), purging (t3), a H2O pulse (t4), diffusion (t5) and purging (t6). Optimal conditions were found by varying the ALD process parameters that resulted in an uniform coating, which protects the QDs from degradation. The optimal reaction times were found to be t1=0.010 s, t2=5 s, t3= 10 s, t4=0.010 s, t5=5 s, and t6=60 s.