Influence of Oxygen on Sputtered Titanium‐Doped Indium Oxide Thin Films and Their Application in Silicon Heterojunction Solar Cells

Abstract

One of the challenges in fabricating high‐performance n‐type silicon heterojunction (SHJ) solar cells is developing a high‐quality transparent conductive oxide (TCO) electrode. Herein, the development and application of low‐temperature sputtered titanium‐doped indium oxide (ITiO) in n‐type, rear junction SHJ solar cells as a function of the oxygen flow ratio is presented. The microstructure, morphology, and optoelectronic properties are analyzed. The grain size of ITiO thin films decreases rapidly as the oxygen flow ratio is increased. Compared with an indium tin oxide (ITO) thin film, ITiO shows a superior balance in achieving excellent optoelectronic properties by reducing film resistivity but maintaining weak absorption. Higher fill factor is obtained by substituting ITiO for ITO as the front electrode in SHJ solar cells, which is mainly due to the improved carrier transport. Resistivity contributions of front‐side vertical and lateral carrier transport are disclosed by Quokka3 simulation. A champion cell efficiency of 23.81% with ITiO is achieved, which is so far the highest efficiency among the application of ITiO in SHJ solar cells to the best of our knowledge. The study demonstrates that ITiO is a promising TCO candidate for SHJ solar cells.