Printable solar cells just got a little closer

[OKIsItJustMe]

http://news.engineering.utoronto.ca/printable-solar-cells-just-got-little-closer/?_ga=1.195331948.1180808848.1486483274

[font face=Serif]Posted February 16th, 2017 by Tyler Irving

[font size=5]Printable solar cells just got a little closer[/font]

[font size=3]A U of T Engineering innovation could make building printing cells as easy and inexpensive as printing a newspaper. Dr. Hairen Tan and his team have cleared a critical manufacturing hurdle in the development of a relatively new class of solar devices called perovskite solar cells. This alternative solar technology could lead to low-cost, printable solar panels capable of turning nearly any surface into a power generator.

…

The new nanoparticles are coated with a layer of chlorine atoms, which helps them bind to the perovskite layer on top — this strong binding allows for efficient extraction of electrons. In a paper recently published in Science, Tan and his colleagues report the efficiency of solar cells made using the new method at 20.1 per cent.

“This is the best ever reported for low-temperature processing techniques,” says Tan. He adds that perovskite solar cells using the older, high-temperature method are only marginally better at 22.1 per cent, and even the best silicon solar cells can only reach 26.3 per cent.

Another advantage is stability. Many perovskite solar cells experience a severe drop in performance after only a few hours, but Tan’s cells retained more than 90 per cent of their efficiency even after 500 hours of use. “I think our new technique paves the way toward solving this problem,” says Tan, who undertook this work as part of a Rubicon Fellowship.

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http://dx.doi.org/10.1126/science.aai9081

[PoliticAverse]

1. Doesn't printer ink already cost more than a solar cell? n/t

[NNadir]

2. Here's some process chemistry from the original paper.

We devised a synthetic approach to obtain Cl-capped TiO2 NCs as the ESL in solar cells. We first synthesized ~5-nm-diameter anatase TiO2 NCs (fig. S2) (38) via a nonhydrolytic method through the reaction of TiCl4 and benzyl alcohol at 85°C under ambient atmosphere (42, 43). This process resulted in Cl-capped TiO2 NCs (TiO2-Cl) with 12 ± 2 atomic % of Cl relative to Ti atoms, as determined by x-ray photoelectron spectroscopy (XPS) (Fig. 1C). A mixture of methanol and chloroform was used to disperse the NCs while preserving surface Cl ligands. XPS confirmed that surface Cl ligands were well retained after we formed films from a methanol chloroform cosolvent (Fig. 1C). In contrast, the surface Cl ligands were detached from TiO2 surfaces when the washed NCs were redispersed in ethanol with a stabilizer such as titanium diisopropoxide bis(acetylacetonate) (TiAcAc). Such TiO2 NCs that lack Cl ligands—the ESL materials used in previous reports (8, 9)—were taken as controls in the present study. Henceforth, we refer to the TiO2 ESL with Cl ligands as TiO2-Cl and the TiO2 ESL lacking the Cl ligands as TiO2. The Cl atoms were strongly bound to TiO2, and the Cl ligands of TiO2 thin film were retained on the surface after annealing up to 250°C (Fig. 1D). We fabricated planar PSCs with TiO2 as the ESL with the device architecture of Fig. 2A. The TiO2-Cl film on indium tin oxide (ITO)– coated glass obtained by spin-coating was smooth and pinhole-free (Fig. 2B and fig. S3A). The film also exhibited negligible parasitic absorption loss over the entire visible–to–near-infrared spectral range (fig. S3B). Post-annealing treatment at moderate temperatures was applied to improve the quality of the spin-cast TiO2-Cl film.

NC stands for nanocrystal, in case you were wondering.

Mmmmm...chloroform.

Solar chemistry is usually pretty filthy even though it's um, said to be "green" and "renewable" which is, basically garbage.

God forbid that this chemistry ever becomes mainstream. The atmosphere, already trashed and weakened, couldn't take it.

The best part of this "almost here" "renewable" scheme is the deposition on ITO, Indium tin oxide.

The world supply of indium is thought to be sustainable for less than ten years.

So much for, um, "renewable."

All this wishful thinking, decade after decade after decade, and we've surged past 400 ppm and no one now living will ever see a level below that.

One thing we can say, we are getting what we deserve. I'm not sure this is true of future generations, if there should be very many of them, but this "little closer" had better be "far away" or God help us.