A novel Al and Y codoped ZnO/n-Si heterojunction solar cells fabricated by pulsed laser deposition

Al and Y codoped ZnO (AZOY) transparent conducting oxide (TCO) thin films were first deposited on n-Si substrates by pulsed laser deposition (PLD) to form AZOY/n-Si heterojunction solar cells. However, the properties of the AZOY emitter layers are critical to the performance of AZOY/n-Si heterojunction solar cells. To estimate the properties of AZOY thin films, films deposited on glass substrates with various substrate temperatures (Ts) were analyzed. Based on the experimental results, optimal electrical properties (resistivity of 2.8 ± 0.14 10 4 X cm, carrier mobility of 27.5 ± 0.55 cm2/Vs, and carrier concentration of 8.0 ± 0.24 1020 cm 3) of the AZOY thin films can be achieved at a Ts of 400 C, and a high optical transmittance of AZOY is estimated to be >80% (with glass substrate) in the visible region under the same Ts. For the AZOY/n-Si heterojunction solar cells, the AZOY thin films acted not only as an emitter layer material, but also as an anti-reflected coating thin film. Thus, a notably high short-circuit current density (Jsc) of 31.51 ± 0.186 mA/cm2 was achieved for the AZOY/n-Si heterojunction solar cells. Under an AM1.5 illumination condition, the conversion efficiency of the cells is estimated at only approximately 4% (a very low open-circuit voltage (Voc) of 0.24 ± 0.001 V and a fill factor (FF) of 0.51 ± 0.011) without any optimization of the device structure. 2012 Elsevier Ltd. All rights reserved.