Researchers from India's University of Calcutta have developed a flexible, lead-free perovskite solar cell that combines recycled indium tin oxide, a PET substrate, and a barium-doped Cs2SnCl6 absorber to deliver a power conversion efficiency of 4.95%, up from 0.79% for the undoped material. The study also shows that the device retains stability over 30 days and remains mechanically robust after 100 bending cycles, pointing to a credible route toward wearable, low-toxicity photovoltaics.
The team emphasized the use of indium tin oxide reclaimed from electronic waste, rather than freshly manufactured ITO. That transparent electrode is deposited on a PET plastic substrate, which keeps the device lightweight and flexible while also lowering the environmental footprint of the stack. The absorber is a lead-free double-perovskite composition, Cs2(BaxSn1-x)Cl6 with x=0.1, so 10% of the Sn site is replaced by Ba.
The incorporation of Ba reportedly improves the structural and optoelectronic quality of Cs2SnCl6. Raman, photoluminescence, and UV-visible measurements confirm that the doped film has better optical behavior, while electron microscopy and compositional analysis show more uniform morphology and improved crystallization. In practical terms, this means the film is better at forming a continuous absorber layer with fewer defects that would otherwise trap charge carriers and suppress current output.
The efficiency jump is large relative to the baseline: 4.95% for the Ba-doped device versus 0.79% for the undoped counterpart. That improvement is consistent with the paper’s mechanism, which links Ba addition to defect passivation, suppression of phase separation, and more effective carrier trapping and extraction in the finished device. The result is especially meaningful for a flexible, lead-free architecture, where many candidate materials struggle to balance toxicity, stability, and efficiency at the same time.
Mechanical testing shows the device performs better after 100 bending cycles, which the authors attribute to lattice softening and a tolerance factor moving closer to unity. That matters because flexible photovoltaics often fail not just from electrical loss, but from cracking, delamination, or microstructural damage during repeated bending. The reported 30-day stability is also important, since flexible perovskite devices are often challenged by moisture, film instability, and interfacial degradation.
This work fits a broader push toward circular photovoltaic manufacturing, where recycled electrodes, low-temperature processing, and lead-free absorbers reduce both material and environmental cost. The combination of e-waste-derived ITO, PET, and a tin-based perovskite modified with just 10% Ba makes the device concept unusually aligned with sustainability goals. At the same time, the study shows that environmental design choices do not have to come at the expense of function, since the final device still reaches a usable photovoltaic performance level for flexible applications.
