The impact of vacuum pressure on efficiency and long-term performance of perovskite solar cells fabricated using chemical vapor deposition technique

Perovskite solar cells (PSCs) have emerged as a leading candidate for the next generation of solar cells. Even though their efficiency has risen from 3.8% to over 25.7%, stability is still a hurdle when commercialization. Chemical vapor deposition (CVD) is a promising method for fabricating high-quality perovskite films. In this study, the CVD technique is utilized to deposit the perovskite layer, and the effect of vacuum pressure on the performance of the solar cells is investigated. The layered structure for a complete solar cell is fluorine-doped tin oxide (FTO)/titanium dioxide (TiO2)/perovskite/graphite/FTO. The CH3NH3PbI3−xClx perovskite films are synthesized by exposing lead iodide (PbI2) and dopant lead chloride (PbCl2) precursor-coated TiO2 substrate to methyl ammonium iodide (CH3NH3I) vapor in the CVD chamber under three different vacuum pressures (0.07 mbar, 0.50 mbar, and 1.00 mbar). The prepared perovskite films were characterized using X-ray diffractometer and scanning electron microscope (SEM). The optimized best device fabricated under 0.50 mbar pressure exhibits the highest power conversion efficiency (PCE) of 1.23%, short circuit current density (Jsc) of 4.56 mA cm^-2, fill factor (FF) of 0.506, and open circuit voltage (Voc) of 0.532 V. Moreover, it recorded the best stability in ambient air by retaining 60.25% of its initial efficiency even after 500 h confirming the direct impact of vacuum pressure on the stability of the perovskite film.