knjiga solarna energija dobra

SOLAR CELL FUNDAMENTALS 91
The solutions to the minority-carrier diffusion equation, equations (3.106)
and (3.107), can be used to evaluate the minority-carrier current densities, equations
(3.110) and (3.111). These can then be substituted into equation (3.116), which,
with some algebraic manipulation, yields
I = I SC − I o1 (e qV/kT − 1) − I o2 (e qV/2kT − 1) (3.118)
where I SC is the short-circuit current and is the sum of the contributions from each of
the three regions: the n-type region (I SCN ), the depletion region (I SCD = AJ D ), and the
p-type region (I SCP )
I SC = I SCN + I SCD + I SCP (3.119)
where
⎡
p ′ (−x N )T p1 − S F,eff p ′ dp ′
(−W N ) + D p
∣
dx
I SCN = qAD p ⎢
⎣
L p T p2
∣
x=−WN
− dp′
dx
⎤
∣ ⎥
x=−xN ⎦
(3.120)
with
T p1 = D p /L p sinh[(W N − x N /L p ] + S F,eff cosh[(W N − x N /L p ] (3.121)
T p2 = D p /L p cosh[(W N − x N )/L p ] + S F,eff sinh[(W N − x N )/L p ] (3.122)
and
⎡
n ′ (x P )T n1 − S BSF n ′ dn ′
(W P ) + D n
∣
dx
I SCP = qAD n ⎢
⎣
L n T n2
∣
x=WP
+ dn′
dx
⎤
∣ ⎥
x=xP
⎦
with
(3.123)
T n1 = D n /L n sinh[(W P − x P )/L n ] + S BSF cosh[(W P − x P )/L n ] (3.124)
T n2 = D n /L n cosh[(W P − x P )/L n ] + S BSF sinh[(W P − x P )/L n ] (3.125)
I o1 is the dark saturation current due to recombination in the quasi-neutral regions,
I o1 = I o1,p + I o1,n (3.126)
with
{ }
I o1,p = qA n2 i
D p Dp /L p sinh[(W N − x N )/L p ] + S F,eff cosh[(W N − x N /L p ]
N D L p D p /L p cosh[(W N − x N )/L p ] + S F,eff sinh[(W N − x N )/L p ]
(3.127)