Simple-Structured Low-Cost Dopant-Free Hole-Transporting Polymers for High-Stability CsPbI₂Br Perovskite Solar Cells

Abstract

Among the solution-processed devices, perovskite solar cells (PSCs) exhibit the highest power conversion efficiency (PCE) of over 25%; tremendous efforts are being undertaken to improve their stability. Recently, all-inorganic CsPbI2Br-based PSCs were reported to exhibit a significantly improved device stability, with a promising PCE of up to 16.79%. In this study, we report stable all-inorganic PSCs by incorporating novel dopant-free hole-transporting materials (HTMs). The synthesis strategy of the newly synthesized polymeric HTMs was similar to that of 2,2′,7,7′-tetrakis­(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene (spiro-OMeTAD), with the exception that they were designed to exhibit dopant-free characteristics. In particular, their polymeric backbone structure was significantly simpler than that of spiro-OMeTADs, and they were easily synthesized in two steps from commercially available chemicals, with an overall yield of ∼50%. The cost of synthesis at the laboratory scale was calculated to be at least 2.4 times cheaper than that of spiro-OMeTADs. The PCE of dopant-free HTM-based PSCs was 11.01%, which is 1.5 times higher than that of the dopant-free spiro-OMeTAD-based devices (7.52%) and comparable to that of the doped spiro-OMeTAD-based devices (12.22%). Notably, the stability of the device based on our dopant-free HTM to atmospheric oxygen and moisture as well as heat and light irradiation was superior to that of devices based on doped and dopant-free spiro-OMeTAD HTMs. On consideration of the synthesis cost, device efficiency, and device stability, our dopant-free HTM is highly promising for all-inorganic PSCs.

Inorganic CsPbI2Br halide perovskites: from fundamentals to solar cell optimizations

“…Moreover, the device under investigation also demonstrated excellent stability in ambient and N 2 atmospheres. 70 Later, the Ni-based polymer HTL of bis(4-dimethylaminodithiobenzil) nickel (II) (BDMA) (Fig. 4e) was developed.…”

Self-Assembled Monolayer-Based Hole-Transporting Materials for Perovskite Solar Cells

“…Perovskite crystals are one of the hottest materials for solution-processible electronic devices such as solar cells, photodetectors, transistors, and light-emitting diodes due to their high performance, which is comparable to that of existing silicon-based devices [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ]. Among the various applications, perovskite solar cells (PSCs) have achieved remarkable progress, and the power conversion efficiency (PCE) of PSCs has dramatically increased over the past decade, now reaching a PCE value of 25.2%, which is comparable to that of commercialized silicon solar cells [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ].…”

Organic bromide solutions-processed all-inorganic perovskite for efficient and stable photovoltaics

“…In the past decade, the power conversion efficiency (PCE) of organic-inorganic hybrid perovskites (OIPs) manufactured using the solution method has increased considerably, from 3.8% to 25.7% [1][2][3][4][5][6][7], and the stability of solar cells has increased. Nonetheless, the volatility of organic cations ((FA + ) (NH 2 ) 2 CH 2 + or (MA + ) CH 3 NH 3 + ) in conventional OIPs has a significant impact on the thermal stability of OIP * Authors to whom any correspondence should be addressed.…”