如何在varchar列中使用Laravel whereYear？

I want to filter the year in my varchar column named schedule using laravel whereYear(). However it returns an error shown in the image below. One more thing is that, I am not pointing the whereYear to created_at date column in the database that everyone is using. Below is my code. Please help. Thanks.

Controller:

$year = $request['bill_year'];
$month = $request['bill_month'];
$period = $request['bill_period'];

if( is_numeric($year) ){

      $amortizations = Amortization::whereYear('schedule', $year)->where('bill_status',0)->get();

      if($amortizations){
         $notification = "Success";
       } else{
         $notification = "Failed";
       }

       return json_encode(array('notify'=>$notification, 'amortizations' => $amortizations, 'year' => $year, 'month' => $month, 'period' => $period));                                           
}

Column 'schedule' in the database

enter image description here

error:

enter image description here

error using answer by Akash Kumar Verma enter image description here

WhereYear working with Y-m-d H:i:s timestamp format

use DB;

$amortizations = Amortization::where( DB::raw('YEAR(schedule)'), $year )->where('bill_status',0)->get();

or

$amortizations = Amortization::whereRaw('YEAR(schedule) = '.$year)->where('bill_status',0)->get();