What would be the PostgreSQL database connection string equivalent for a known sqlserver connection string

I have a c#  application which needs to write into sqlserver  and postgresql  databases.

I  use Dapper  ORM

I have been able to specify my connection string   for sqlserver  and it works

Now i am trying to specify  the equivalent  for  PostgreSQL  and I am getting the

Error   " OLE DB Provider  not Specified in the Connection String "

I have tried the following 3  providers

providerName="Npgsql2" />
providerName="Npgsql" />
providerName="SQLOLEDB" />

with same error message

Whats should be my provider string  for a c# application  connection to a

PostgreSQL database  using Dapper

Please Note that  I have Dapper  and   Npgsql installed in my application using Nuget

Attached please find error screen using the debugger and my connection string PostgreSQL

I will be grateful for an assistance

O.A.  Oluwole
OLE-DB-PROVIDER--24-09-2018.docx