Plant Sunscreen and Co(II)/(III) Porphyrins for UV‐Resistant and Thermally Stable Perovskite Solar Cells: From Natural to Artificial

Abstract

The poor UV, thermal, and interfacial stability of perovskite solar cells (PSCs) makes it highly challenging for their technological application, and has drawn increasing attention to resolving the above issues. In nature, plants generally sustain long exposure to UV illumination without damage, which is attributed to the presence of the organic materials acting as sunscreens. Inspired by the natural phenomenon, a natural plant sunscreen, sinapoyl malate, an ester derivative of sinapic acid, is employed to modify the surface of electron transport materials (ETMs). The interfacial modification successfully resolved the UV stability and reduced the poor interfacial contact between ETM and perovskite. The best efficiency of fabricated PSCs is up to 19.6%. Furthermore, we employed a mixture of Co(II) and Co(III)-based porphyrin compounds containing the excellent Co(II)/Co(III) redox couple to substitute the commonly used hole transport material, 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9-spiro-bifluorene (spiro-OMeTAD), to resolve the thermal degradation of PSCs noted at and above 80 °C that originates from ion diffusion of I and CH NH (MA ) ions from perovskite into spiro-OMeTAD. Finally, the stable PSCs with the best efficiency up to 20.5% are successfully fabricated.

Efficient Bifacial Passivation with Crosslinked Thioctic Acid for High‐Performance Methylammonium Lead Iodide Perovskite Solar Cells

“…[36,42] Therefore, TA tends to anchor on the TiO 2 surface. It is well known that the carboxylic acid moieties (COOH) can be efficiently bonded to the TiO 2 surface through the coordination effect.…”

Hole Transport Materials in Conventional Structural (n–i–p) Perovskite Solar Cells: From Past to the Future

“…This result is attributable to a much more robust and hydrophobic WT3 layer on the perovskite layer. The dopant‐free Co(II) and Co(III) porphyrins have recently been reported in combination with sinapoyl malate, which is a natural plant sunscreen, on a mesoporous TiO 2 layer . The mixture of Co(II) and Co(III) ions was excellent for the oxidation and reduction processes, achieving 20.5% of efficiency in Per‐SC (Figure e).…”

Major Impediment to Highly Efficient, Stable and Low-Cost Perovskite Solar Cells

“…The efficiencies of PSCs with TiS 2 were decayed by only about 10% from its maximum value after continuous illumination under UV light for 50 h. Unlike the replacement of the TiO 2 ETL, Tsai et al introduced biaxially-extended octithiophene-based conjugated polymers which could filter UV light in inverted PSCs, in other words, the irradiation of UV light could be blocked by HTL [99]. There are some other reports that used down-conversion materials and a UV-blocking layer in PSCs to improve stability in UV light [100,101]. and H + (Equation 7).…”