Enhancing photovoltaic performance of carbon-based planar Cs₃Sb₂I_9-xCl_x solar cells by using P3HT as hole transport material

The existence of toxic lead (Pb) remains a main handicap to the commercial application of perovskite solar cell (PSC). Although antimony (Sb)-based all-inorganic perovskite-like solar cells can overcome the toxicity and instability of hybrid Pb-based PSC, the Sb-based all-inorganic cell presents poor photoelectric conversion efficiency (PCE). Herein, we report a novel strategy that adopts poly (3-hexylthiophene) (P3HT) to modify the Cs₃Sb₂I_9−xCl_x/carbon interface in carbon-based planar Cs₃Sb₂I_9−xCl_x solar cells. It was found that the Cs₃Sb₂I_9−xCl_x solar cell comprising P3HT exhibits less V_oc deficit and higher PCE (1.67%). The mechanism behind performance improvement of P3HT-based Cs₃Sb₂I_9−xCl_x device is suitable energy level position and high hole transport rate with low recombination. Moreover, the introduction of the P3HT layer has no negative impact on the stability of the carbon-based planar Cs₃Sb₂I_9−xCl_x device.