Formation of robust junction between Cu(InGa)Se2-based absorber and Zn(O,S,OH)x buffer prepared on a 30 cm×30 cm submodule

An important key to realize the strong requirement on the electrical yield (i.e. 85 % in the efficiency of over 10 % in 30 cm×30 cm-sized CIGS-based circuits with an aperture area of over 810 cm²) has been indicated to make a robust junction between CIGS-based absorber and Zn(O,S,OH)_x buffer. In this study, the baseline process for CBD-Zn(O,S,OH)_x buffer deposition is investigated from the standpoint of reduction of the deviation of FF. By monitoring the transparency or transmittance (%T) of the CBD solution as a new control parameter, the Zn(O,S,OH)_x buffer deposition process is much stabilized especially on the thickness uniformity measured by LBIC technique. From this approach, it is confirmed that much narrower distribution of FF in the range of over 0.6 can be steadily achieved by improving the thickness uniformity of the buffer and, as a result, the achievement of the above goal is foreseeable