Structural, morphological, photoluminescence and electrical characterization of aluminium doped ZnO phosphors for solar cell applications

We report synthesis of highly luminescent and n-type conducting aluminium doped ZnO (AZO) phosphors using flux-free solidstate reaction technique followed by casting of thin films. The precursor powders were pelletized and fired at 1000 degrees C (AZO-1). In another typical case, 2-stage sequential firing has been adapted at 1000 degrees C followed by 1200 degrees C (AZO-2) in a flowing O2 gas environment. The stabilization (dwell) time has been fixed as 2 hours for all temperatures of firing in the furnace. After firing at 1200 degrees C, a new cubic phase (zinc aluminate) has been observed in the lattice along with the wurtzite ZnO phase. The microstructure analysis was substantiated with Rietveld refinement of the diffraction data of AZO-1 and AZO-2 samples. The photoluminescence (PL) measurements revealed that both AZO-1 and AZO-2 exhibited green (similar to 523 nm) PL under UV (375 nm) excitation, with emission intensity of AZO-1 comparatively higher than that of AZO-2 sample. Moreover, the measurement of electronic transport properties of the AZO-1 and AZO-2 samples exposed their n-type behavior, with slightly lower electrical resistivity of AZO-1 (4.7 x 10(-3)Omega-m) as compared to AZO-2 (3 x 10(-3)Omega-m) at 700 K temperature. The AZO samples have been used as target materials for transparent thin film deposition on quartz substrate, thus proving it to be ideal materials for solar cell applications. (c) 2017 Elsevier Ltd. All rights reserved.