3.3 Performance of large-area SCH solar cell
Using HWOSD to prepare MoOx HTL, the large-area (M6/166mm) MoOx/c-Si(n) SCH solar cells with the front-contact back-junction structure were fabricated according to the optimal process flow as shown in Fig. 1. PV parameters of five SCH solar cells are shown in Table 1. The light J-V and EQE curves for the champion solar cell with Voc of 709 mV, Jsc of 39.57 mA/cm2, FF of 76.9 %, and PCE of 21.59 % are plotted in Fig. 5(a) and (b), respectively. As a reference, the light J-V and EQE of a SHJ solar cell with the same size as the SCH solar cells and with a PCE of above 25% are provided in Fig. 5. At present stage, all the PV parameters of the champion SCH solar cell are lower than those of the reference SHJ solar cell. The significantly lower FF could be partly attributed to the relatively high contact resistance between MoOx and ICO. The lower Voc should be related to the screen printing and subsequent annealing process for preparing the Ag grids. This process is prior to the MoOx HTL deposition to avoid the deterioration of the MoOx layer caused by the 200oC annealing. Thereby, high-density defect states may appear at the a-Si:H(i)/MoOx interface due to the damage to the exposed a-Si:H(i) layer. The slightly lower Iscis due to the slightly lower long wavelength EQE as can be seen in Fig. 5 (b). In order to improve the device performance, the development of new TCO films that are beneficial for low contact resistance, and a low-temperature grids process capable of avoiding MoOxdeterioration are urgently needed. The potential Voc of up to 752 mV under 1 sun illumination indicates the performance potential for further development of the SCH solar cells(Figure S1) .
Table 1 Performance parameters of large-area MoOx/c-Si(n) SCH solar cells