PHP Codeigniter is showing the cache when i press the back button after I logout

[eluser]Unknown[/eluser]
After I logout from my app, when I press the back button, all of the login options for the user is still showed on the page.

After I login, when I press the back button it will show the logout version of the page.

I tried setting this in my logout controller

Code:

function logout() {
    $this->output->set_header('cache-Control: no-store, no-cache, must-revalidate');
    $this->output->set_header("cache-Control: post-check=0, pre-check=0", false);
    $this->output->set_header("Pragma: no-cache");
    $this->output->set_header("Expires: Sat, 26 Jul 1997 05:00:00 GMT");
    $this->tank_auth->logout();
    redirect(subdomain() . 'home');
}

But the cache is still there when i press the back button. How can i fix this?

-----UPDATE------

I think caching is not the problem here, I disabled caching in chrome in developer settings but my browser is still going to the secured page after logout when i press the back button.

So caching is not the problem..

----UPDATE2------

Caching is the problem! I fixed this by putting this code in the index.php file of codeigniter

Code:

header("Expires: Thu, 19 Nov 1981 08:52:00 GMT");
header("Cache-Control: no-store, no-cache, must-revalidate");

So the problem is solved!