In[29]= h = 6.626*10^-34;    
    q = 1.6*10^-19;    
    k = 1.38*10^-23;   
    c = 3*10^8;   
    ts = 6000;   
    fw = 2.18*10^-5;   
    te = 300;   
    ms = (k*ts);     
    me = (k*te);   
    vol2 = (q*v2)/(k*te);   
    vol1 = (q*v1)/(k*te);     
    Eg1 = Input[]       
    Eg2 = Input[]          
    nu1ts = (Eg1*q)/(k*ts);   
    nu2ts = (Eg2*q)/(k*ts);   
    nu1te = (Eg1*q)/(k*te);    
    nu2te = (Eg2*q)/(k*te);    
    qi1te = NIntegrate[(x^2)/(-1 + (Exp[x])), {x, nu1te, Infinity}];           
    qs1te = (qi1te*2*\[Pi]*(me^3))/((h^3)*(c^2))       
    f01 = 2*qs1te;      
    i01 = q*f01;         
    qi2te = NIntegrate[(x^2)/(-1 + (Exp[x])), {x, nu2te, Infinity}];        
    qs2te = (qi2te*2*\[Pi]*(me^3))/((h^3)*(c^2))        
    f02 = 2*qs2te;        
    i02 = q*f02;          
    qi1ts = NIntegrate[(x^2)/(-1 + (Exp[x])), {x, nu1ts, Infinity}];            
    qs1ts = (qi1ts*2*\[Pi]*(ms^3))/((h^3)*(c^2))       
    qi12ts = NIntegrate[(x^2)/(-1 + (Exp[x])), {x, nu2ts, nu1ts}]        
    qs12ts = (qi12ts*2*\[Pi]*(ms^3))/((h^3)*(c^2))          
    (*fs1=(fw*qs1ts)+(qs1te*Exp[vol2])            
    fs2=(fw*qs12ts)+(qs1te*Exp[vol1])*)           
    NSolve[{(1 + vol1)*
         Exp[vol1] - ((((fw*qs1ts) + (qs1te*Exp[vol2]))/f01)) - (.5*vol2*
          Exp[vol1]) == 
       0, (1 + vol2)*
         Exp[vol2] - ((((fw*qs12ts) + (qs1te*Exp[vol1]))/
           f02)) - ((qs1te/qs2te)*.5*vol1*Exp[vol2]) == 0}, {vol1, vol2}]             

    take Eg1=1.7       
    and Eg2=1.12       
    NSolve::ivar: 38.6473 v1 is not a valid variable. >>          
    NSolve[{-225.314 (2.18383*10^21 + 0.00221913 E^(38.6473 v2)) + 
        E^(38.6473 v1) (1 + 38.6473 v1) - 19.3237 E^(38.6473 v1) v2 == 
       0, -9.40801*10^-8 (1.72614*10^21 + 0.00221913 E^(38.6473 v1)) - 
        8.06863*10^-9 E^(38.6473 v2) v1 + 
        E^(38.6473 v2) (1 + 38.6473 v2) == 0}, {38.6473 v1, 38.6473 v2}]            

but does not give any solution for v1 and v2

Attachments: