Solar Energy, Vol.86, No.11, 3146-3152, 2012
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 (T-s) were analyzed. Based on the experimental results, optimal electrical properties (resistivity of 2.8 +/- 0.14 x 10(-4) Omega cm, carrier mobility of 27.5 +/- 0.55 cm(2)/Vs, and carrier concentration of 8.0 +/- 0.24 x 10(20) cm(-3)) of the AZOY thin films can be achieved at a T-s of 400 degrees C, and a high optical transmittance of AZOY is estimated to be >80% (with glass substrate) in the visible region under the same T-s. 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 (J(sc)) of 31.51 +/- 0.186 mA/cm(2) 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 (V-oc) of 0.24 +/- 0.001 V and a fill factor (FF) of 0.51 +/- 0.011) without any optimization of the device structure. (c) 2012 Elsevier Ltd. All rights reserved.