Antimony incorporated flexible Cu2ZnSn(S,Se)4 solar cell for enhanced mechanical endurance and efficiency

Balancing the efficiency and mechanical endurance of flexible Cu2ZnSn(S,Se)4 (CZTSSe) thin film solar cells is challenging its potential applications of the day. Here, a straightforward strategy is developed to prepare flexible solar cells with the coexistence of photovoltaic performance and flexibility by introducing a novel SbCl3 in precursor solution. Sb-doped CZTSSe thin film with progressive grain growth from nanoscale to microscale and strengthened toughness with porosity from 8.13 % to 2.44 % is obtained. By exploiting the benefits of upgrading the band matching and tailoring the residual stress, SbCl3 solution with a concentration of 0.30 mol/L achieves the optimum heterojunction characteristic and mechanical performance. The final structured device with improved efficiency from 3.27 % to 4.98 % and indomitable mechanical endurance is attained, which can reserve 93 % of its original efficiency after bending 200 times. The present work indubitably paves a convenient way toward efficient and flexible photovoltaic devices.