Tuning the Optoelectronic Properties of ZnO:Al by Addition of Silica for Light Trapping in High‐Efficiency Crystalline Si Solar Cells. Issue 3 (19th November 2015)

• Record Type: Journal Article
• Authors: Dabirian, Ali; Martin de Nicolas, Silvia; Niesen, Bjoern; Hessler‐Wyser, Aïcha; De Wolf, Stefaan; Morales‐Masis, Monica; Ballif, Christophe
• Is Part Of: Advanced materials interfaces. Volume 3:Issue 3(2016)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2015-11-19
• Subjects: heterojunction silicon solar cells -- solar cells, light trapping -- refractive index tuning -- transparent conductive oxides; Materials science -- Periodicals; 620.11
• DOI: 10.1002/admi.201500462
• Languages: English
• ISSNs: 2196-7350

Abstract

Abstract : Highly transparent electrodes with a well‐tuned refractive index are essential for a wide range of optoelectronic devices, such as light emitting diodes and solar cells. Here, it is shown that the transparency of ZnO:Al can be improved and its refractive index can be reduced simultaneously by the addition of SiO2 into the layer. It is found that for low SiO2 concentrations, Si quenches oxygen vacancies and improves the layer transparency. At higher SiO2 concentrations a highly transparent amorphous compound of Zn x Si y O:Al forms, with a refractive index that scales down with the relative Si/Zn ratio. These layers are tested in Si heterojunction solar cells by inserting them between Si and the metallic rear contact of such devices. A consistent improvement is found in the cell short‐circuit current density and external quantum efficiency with increasing Si incorporation. Our findings establish a general strategy to tune the optical properties of transparent conductive oxides for improved light management in solar cells. Abstract : Transparent conductive oxides with tunable refractive index and optical transparency are obtained by adding the highly transparent and low‐refractive SiO2 to ZnO:Al. Si has different functions in ZnO:Al depending on its concentration. A ZnO:Al layer with an optimized SiO2 concentration significantly improves the infrared external quantum efficiency of a c‐Si heterojunction solar cell.