Loop to assign a value if an observation in one column is equal to other column's name in R

I have a vector and a data set that are similar to:

id_vector <- as.character(c("n01", "n02", "n03"))
df_1 <- data.frame("id" = c("n01", "n02", "n02", "n03"), "n01" = NA, "n02" = NA,  "n03" = NA)
df_1$id <- as.character(df_1$id)

And I want the data set to be:

df_2 <- data.frame("id" = c("n01", "n02", "n02", "n03"), "n01" = c(1, NA, NA, NA), "n02" = c(NA, 1, 1, NA),  "n03" = c(NA, NA, NA, 1))

The solution should be simple, something like:

for (i in id_vector){
  df_1[i][df_1$id == i] <- 1
}

However, I can't use two []s. The error is:

Error in `[<-.data.frame`(`*tmp*`, df_1$id == i, value = 1) : 
duplicate subscripts for columns 

Any help?

Thanks!