Low-temperature, solution processed device quality CZTS film for efficient heterojunction solar cells

We report the preparation of device quality CZTS films by dip coating of a highly stable precursor solution followed by annealing at very low temperature of only 100°C.We also demonstrate that, the films can be used to make simple CZTS-CdS heterojunction based efficient solar cells. Initial devices with aluminium top contacts showed the best photovoltaic performance reported for this type of devices with power conversion efficiency (PCE) of 2.73%. In addition to fully avoiding the sulphurization/selenization step and the toxic solvents, our method to deposit the kesterite functional layer has added advantages of exceptional stability of the molecular precursor and the ultra-low temperature of processing suitable for various flexible optoelectronics applications at large scale.