Efficient Solar Cells Employing Light-Harvesting Sb<sub>0.67</sub> Bi<sub>0.33</sub> SI.

Nie, Riming; Im, Jino; Seok, Sang Il · Adv Mater · 2019

basic_science · Level V

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Abstract

Sb<sub>1-</sub> <sub>x</sub> Bi<sub>x</sub> SI, an isostructural material with the well-known quasi-1D SbSI, possesses good semiconductive and ferroelectric properties but is not applied in solar cells. Herein, solar cells based on alloyed Sb<sub>0.67</sub> Bi<sub>0.33</sub> SI (ASBSI) as a light harvester are fabricated. ASBSI is prepared through the reaction of bismuth triiodide in N,N-dimethylformamide solution with an antimony trisulfide film deposited on a mesoporous (mp)-TiO<sub>2</sub> electrode via chemical bath deposition at 250 °C under an argon or nitrogen atmosphere; the alloy exhibits a promising bandgap (1.62 eV). The best performing cell fabricated with poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b']dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] as the hole-transporting layer shows 4.07% in a power conversion efficiency (PCE) under the standard illumination conditions of 100 mW cm<sup>-2</sup> . The unencapsulated cells exhibit good comprehensive stability with retention of 92% of zjr initial PCE under ambient conditions of 60% relative humidity over 360 h, 93% after 1 sun illumination for 1254 min, and 92% after storage at 85 °C in air for 360 h.