How to solve this equation for ( I ) ?

q = 1.602e-19;          k = 1.381e-23;
Tx = 298.15;            Rs = 0.005;                
Io = 1e-9;               n = 1.3;

V = 0:0.1:0.4; 

Isc - I - Io.*( exp((V+(I*Rs))*(q/(n*k*Tx))) -1)==0

[Azzi Abdelmalek]

You have two unknwn variables Isc and I

Answer 1

[the cyclist]

You should be able to use

my_function = @(I) Isc - I - Io.*( exp((V+(I*Rs))*(q/(n*k*Tx))) -1);  
I_solution = fzero(my_function,0)

but as Azzi points out, you have not defined Isc.

Also, you may need to loop over your values of V, for different solutions I.