I just did a quick google search and I saw that PHP Objects, Patterns and Practice is a high rated book, not just for learning php, but for learning OOP (object oriented programming). Found it on amazon here: http://www.amazon.com/dp/143022925X/...ackoverfl08-20
I still encourage you to do a little more researching before purchasing a book. Read the customer reviews and most of the time you can read the table of contents and a portion of the first chapter before purchasing it.