Как записать данные в *.json?

required_account_creating = input('Do you want to make an account in this game? (y/n)')
    if required_account_creating == 'y':
        try:
            playername = input('Create a name for your account. Please remember it: ')
            start_time = datetime.now()
            created_file_name = str(playername + '.json')
            # creating user account's file
            with open(created_file_name, 'wb') as account:
                # Initializing data: (name, statistics, rating)
                contents = {'name': playername, 'all_log-ins': 1, 'longest_game': '', 'most_wins': 0, 'most_lost': 0,
                            'best_game': '', 'worst_game': '', 'rating': 0}
                # writing initialized data into file.
                try:
                    json.dump(contents, account, ensure_ascii=False)
                except:
                    print('Some error appeared when writing data into file. Anyway, file will be created.')
                    account.close()
                    time.sleep(3)
                    quit()

Что я делаю не так?