Ultra-thin Cu(In,Ga)Se₂ (CIGSe) solar cells on transparent conductive oxide back contact reduce the material consumption of rare indium and gallium and simultaneously exhibit great potential for semi-transparent bifacial application. For highly efficient CIGSe solar cells, a steep back Ga grading and Na treatment are expected. However, Na will promote the formation of highly resistive GaO_x at the rear interface owing to Ga accumulation. In this work, the three-stage co-evaporation process is renewed and the effect of the deposition sequence in the first stage on the Ga distribution as well as the cross-correlated influence of Na is explored. In particular, the standard deposition sequence of Ga+In is altered to start with In. When a thin In layer is pre-deposited on the back contact, the fill factor and efficiency increase. The deposition of In+Ga+In in the first stage of CIGSe growth leads to efficiencies 28% (on average) higher than for the standard deposition sequence of Ga+In. Additionally, 2.74% efficiency is reached under rear and 9.32% under simultaneous front and rear illumination. Therefore, adapting the deposition sequence in the first stage of CIGSe growth is identified as a key to improving the device performance on transparent back contact.