Dje was constructed by request of Vuk Stefanović Karadžić.1 There were several proposed shapes of the letter (one by Pavle Solarić, another by Gligorije Geršić). The variant now in use was designed by Lukijan Mušicki;234 it was designed by modification of the letter Ћ, itself a revival of the old Cyrillic letter Djerv (Ꙉ).5 The new letter was adopted in Karadžić's 1818 dictionary and thus entered widespread usage.6 There was also a Д and Ь ligature variant that has not been added in Unicode as a character, and was used before Dje took its current form.
Maretić, Tomislav. Gramatika i stilistika hrvatskoga ili srpskoga književnog jezika, p. 14-15. 1899. ↩
Lalević, Miodrag S. (1953). Potsetnik iz srpskohrvatskog jezika i pravopisa: s pravopisnim i jezičkim savetnikom. Rad. p. 75. Облик му је у Вуковој азбуци дао песник Лукијан Мушицки https://books.google.com/books?id=dWpEAAAAIAAJ ↩
Петар Ђорђић. Историја српске ћирилице. Београд, 1971. ↩