Showing values in attribute table in scientific (exponential) notation in QGIS3

Question

One of my virtual field contains too big numbers like "5994865699857.456". I need to show those values in scientific/exponential mode like 5.99E+12. I didn't find proper function in Field Calculator. I searched for solution among others questions but all questions address inverse problem - converting scientific view to number one, and I didn't find a solution among answers.

Is there some trick in Field Calculator to solve the problem?

Edit: I'd like to see value in scientific notation in Feature Attributes form when I use "Identify Features" function.

Edit2: I also tried to create custom function:

from qgis.core import *
from qgis.gui import *

@qgsfunction(args='auto', group='Custom')
def fd_sci(value1, feature, parent):
    vtostring = str(value1)
    a = "{:.2e}".format(vtostring)
    return a

Then created a new virtual field using expression: fd_sci("virtual_field_with_big_number")

But the result is NULL

Answer 1

Eventually I found what works. Just no need to convert a value to string, and Output field type should be Decimal number (real):

from qgis.core import *
from qgis.gui import *

@qgsfunction(args='auto', group='Custom')
def fd_sci(value1, feature, parent):
    a = "{:.2e}".format(value1)
    return a