High-Quality Zno/Ag/Zno Multilayer by Sputtering and Czts Solar Cells with Excellent Flexibility

In this study, ZnO/Ag/ZnO (ZAZ) films were deposited by RF magnetron sputtering. With increasing Ag thickness, the Ag (111) peak became stronger, but the diffraction peak of ZnO (002) became weaker, and the grain size and roughness of the film increased. Moreover, the sheet resistance and resistivity of ZAZ films decreased significantly with the increased Ag thickness. The average transmission increased first and then reduced, and the mobility and carrier concentration increased. Finite-difference time-domain (FDTD) method was used to simulate the film's transmittance and field strength, verifying the accuracy of the experimental results. The ZnO/Ag(9nm)/ZnO (ZA9Z) film had the optimal photoelectric characteristics: mobility of 13.2 cm2·v-1·s-1, carrier concentration of 7.27×1021 cm-3, resistivity of 9.16×10-5 Ω·cm, and average transmittance of 91.8%, showing a figure of merit value of 50.9 ×10-3 Ω-1. Moreover, the ZAZ film maintained excellent long-term stability within 180 days under 25 °C/65% RH. Compared to the ITO film, the ZAZ film on polyethylene terephthalate (PET) substrates possessed extraordinary flexibility and durability under continuous cyclic bending tests. Moreover, CZTS solar cells (SCs) with ZA9Z film showed a power conversion efficiency (PCE) of 6.69%, which was almost 13% higher than those with ITO film. The ratio of PCE of the SCs with ZA9Z film to that of the SCs with ITO film was 6.88 and 12.31 after a bending diameter of 8mm and 1000 cyclic bending, respectively, showing that the CZTS SCs with ZA9Z film are of excellent flexibility.