R: Scraping aspx from doPostBack

I am trying to scrape this page to download the file in excel.

I've been trying this until now but it doesn't help me:

library(rvest)  

url<-"http://www.smv.gob.pe/Frm_ValorCuotaDetalle_V2.aspx?in_ac_pre_ope=A&tip_fon_desc=TODAS&in_ad_fecha=24/12/2019"

html_nodes(read_html(url), css = "#cbExcel")

I don't know how to add that to download the excel href="javascript:__doPostBack('cbExcel','')

.