I don't know how does Zotero sort the collections.
Mostly, we use alphabetical sequence.
e.g.
My library includes:

@Inbox
CNC
Computer Science
Info
Office Related Application
Research
Tutorial
Virtual Reality

You see, from "CNC" to "Virtual Reality", they are arranged by alphabetical sequence. But I need a new collection named "Inbox" to list at the top of my library. So I add a character "@" before "Inbox", because I think "@" lies before any a-z character in both ASCII and Unicode.

But here is the question:
I want some collections to list at the bottom of my library, named "Later" or "Lower" or something like that. I know that I need some character added before the name of the collection. I tried some characters after "z" (No. 122 in ASCII) and kind-looking like "|", "~", but failed. They are even listed at the top of the library.

Then I tried some characters after "z" in Unicode, like some Chinese words and Greek character. It really works, but looks unsightly and incongruent.

So would you please introduce me a good-looking character listed below "z" ?

Thanks.