Wikipedia article about PhD thesis
No, it would not be advisable to create a Wikipedia page solely devoted to the new technique. If you are one of the sole people responsible for the technique and its development, you run the risk of creating a conflict of interest. Even without that issue, a new technique likely has few published sources to support it, so you will have difficulty establishing notability. Without additional support from reliable sources, your new page may be deleted.
Luckily, there are numerous other options for promoting your work in laymen-friendly ways. It may be feasible (and may even provide better visibility of your work, even to prospective employers) to write a few blog entries about the approach, produce a short Youtube video about it, or even a dedicated wiki, if you see the technique undergoing changes or optimizations in the near future.
Would it be a good idea to make a Wikipedia page on the technique I developed?
No. In the best case scenario (which is also the most likely one in my opinion), one of the Wikipedia editors will delete the page you created, since there are not yet any published papers about the technique you developed so it doesn't even come close to satisfying Wikipedia's notability criteria (which probably wouldn't be satisfied even long after your paper is published, unless your discovery is truly groundbreaking and ends up being cited and used by many people).
In a less ideal scenario, your article won't be deleted. That would be even worse, because anyone who happens on this page will immediately know that you created it, and will conclude that you are some combination of:
Someone with a highly inflated and unrealistic opinion of the value of his work.
Someone who is clueless about the value a scientific work needs to have in order to deserve having a Wikipedia page about it.
Someone who is obsessed with self-promotion to a very unhealthy extent that is an extreme outlier in academia (and frankly has no place in academia in my personal opinion).
Would it be perceived as a signal that I have no good science to show (I don't think so)?
No, but it won't signal that you do have good science, and it would signal several other things about you, none of which are good -- see above.