Efficient, stable and scalable perovskite solar cells using poly(3-hexylthiophene).
basic_science · Level V
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- Record sourced from PubMed, PMID 30918371.
- Also identified by DOI 10.1038/s41586-019-1036-3.
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Abstract
Perovskite solar cells typically comprise electron- and hole-transport materials deposited on each side of a perovskite active layer. So far, only two organic hole-transport materials have led to state-of-the-art performance in these solar cells<sup>1</sup>: poly(triarylamine) (PTAA)<sup>2-5</sup> and 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (spiro-OMeTAD)<sup>6,7</sup>. However, these materials have several drawbacks in terms of commercialization, including high cost<sup>8</sup>, the need for hygroscopic dopants that trigger degradation of the perovskite layer<sup>9</sup> and limitations in their deposition processes<sup>10</sup>. Poly(3-hexylthiophene) (P3HT) is an alternative hole-transport material with excellent optoelectronic properties<sup>11-13</sup>, low cost<sup>8,14</sup> and ease of fabrication<sup>15-18</sup>, but so far the efficiencies of perovskite solar cells using P3HT have reached only around 16 per cent<sup>19</sup>. Here we propose a device architecture for highly efficient perovskite solar cells that use P3HT as a hole-transport material without any dopants. A thin layer of wide-bandgap halide perovskite is formed on top of the narrow-bandgap light-absorbing layer by an in situ reaction of n-hexyl trimethyl ammonium bromide on the perovskite surface. Our device has a certified power conversion efficiency of 22.7 per cent with hysteresis of ±0.51 per cent; exhibits good stability at 85 per cent relative humidity without encapsulation; and upon encapsulation demonstrates long-term operational stability for 1,370 hours under 1-Sun illumination at room temperature, maintaining 95 per cent of the initial efficiency. We extend our platform to large-area modules (24.97 square centimetres)-which are fabricated using a scalable bar-coating method for the deposition of P3HT-and achieve a power conversion efficiency of 16.0 per cent. Realizing the potential of P3HT as a hole-transport material by using a wide-bandgap halide could be a valuable direction for perovskite solar-cell research.