A Universal and Facile Method of Tailoring the Thickness of Mo(S_x,Se_1−x)₂, Contributing to Highly Efficient Flexible Cu₂ZnSn(S,Se)₄ Solar Cells

Abstract

Flexible Cu2ZnSn(S,Se)4 (CZTSSe) solar cells have attracted considerable attention due to their potential application in specific areas such as power sources for wearable electronics. However, the over‐thick Mo(Sx,Se1−x)2 at the back contact is one of the factors that limit the device performance. Herein, a facile strategy to inhibit the thick Mo(Sx,Se1−x)2 layer by adding a proper proportion of sulfur during selenization is reported. It is found that the thickness of Mo(Sx,Se1−x)2 can be effectively tailored via tuning the proportion of S, enabling a substantial decrease in series resistance. The suppression mechanism is mainly ascribed to the change of orientation of Mo(Sx,Se1−x)2 induced by S, which limits the diffusion of Se to Mo. Accordingly, the total area efficiency of the flexible CZTSSe device improves significantly from 5.5 to 8.9% with the addition of 2% S, followed by a drop with more S. Furthermore, it is demonstrated that this strategy can also be applied to both kesterite and chalcogenide absorbers deposited on rigid Mo substrates to suppress the thick Mo(Sx,Se1−x)2 layer, indicating the universality of this method. Overall, this work provides a general, facile, and effective approach to modify the back contact interface without introducing extra blocking layers.

A Critical Review on the Progress of Kesterite Solar Cells: Current Strategies and Insights

“…The MoSe 2 parallel to the substrate may prevent further selenization with a natural barrier, which is also confirmed by other works. [ 158,164 ] Furthermore, Yu et al. investigated the formation mechanism of the multilayer absorber and proposed the MoO 3 isolating layer as a solution.…”

“…The MoSe 2 parallel to the substrate may prevent further selenization with a natural barrier, which is also confirmed by other works. [158,164] Furthermore, Yu et al investigated the formation mechanism of the multilayer absorber and proposed the MoO 3 isolating layer as a solution. [48] The MoO 3 layer prepared by in situ annealing relieved kesterite decomposition and thus eliminated the nucleus centers at the back contact to avoid unfavorable double or triple-layer crystallization.…”

Enhanced photoresponse of Cu2ZnSnS4 absorber thin films fabricated using multi-metallic stacked nanolayers

“…It comprises a less hazardous substance, S, rather than Se, and has a direct bandgap energy of about 1.5 eV and a strong absorption coefficient >10 4 cm −1 in the visible area. [8][9][10][11][12][13] In recent years, by enhancing the synthesis and manufacturing procedure, CZTS-based solar cells' efficiency rose from 0.66% to 12.6%. [14][15][16] Various deposition techniques, solution-based and vacuum process based, [17][18][19][20][21][22] can be used to fabricate CZTS thin lms.…”

10.24% Efficiency of Flexible Cu2ZnSn(S,Se)4 Solar Cells by Pre‐Evaporation Selenization Technique

“…DOI: 10.1002/smll.202201347 high light absorption coefficient, and rich reserves. [1][2][3][4][5][6][7] The CZTSSe absorber layers can be fabricated on flexible substrates, such as Mo foils, [8][9][10] Ti foils, [11,12] and stainless steel foils, [13,14] to obtain flexible solar cells. Owing to the high power-tomass ratio and low cost, flexible CZTSSe solar cells show large potential in the applications of building photovoltaic integration, wearable devices, and military equipment.…”

“…Owing to the high power-tomass ratio and low cost, flexible CZTSSe solar cells show large potential in the applications of building photovoltaic integration, wearable devices, and military equipment. [15][16][17] As Mo foils have advantages such as superb flexibility and hightemperature resistance, Mo-foil-based flexible CZTSSe solar cells have developed rapidly [8,9,18] and reached a power conversion efficiency (PCE) of 11.19%. [10] Compared with the Shockly-Quesser (SQ) limit efficiency (33%), the flexible CZTSSe devices have severe open-circuit voltage (V OC ) loss.…”