Ireland is not a member of the Schengen Area and a Schengen visa is not valid for travel to Ireland. A passport is required for travel to Ireland from any other state (including the United Kingdom where it is not an immigration requirement, but airlines require identification documents and many will only accept a passport).
Please see this advice from the Irish government on whether or not you need to apply for a visa in advance of travel to Ireland to attend an academic conference, according to your nationality as shown on your passport or travel document. Participants who do need a visa can find advice here on the online application process and the likely duration of the wait for approval (typically about 8 weeks according to the immigration service). If you need an invitation letter from the conference organisers, please send an email to firstname.lastname@example.org, with “visa letter” in the subject line.