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@ARTICLE{Xiao:878470,
author = {Xiao, Biao and Calado, Philip and MacKenzie, Roderick C. I.
and Kirchartz, Thomas and Yan, Jun and Nelson, Jenny},
title = {{R}elationship between {F}ill {F}actor and {L}ight
{I}ntensity in {S}olar {C}ells {B}ased on {O}rganic
{D}isordered {S}emiconductors: {T}he {R}ole of {T}ail
{S}tates},
journal = {Physical review applied},
volume = {14},
number = {2},
issn = {2331-7019},
address = {College Park, Md. [u.a.]},
publisher = {American Physical Society},
reportid = {FZJ-2020-02874},
pages = {024034},
year = {2020},
abstract = {The origin of the relationship between fill factor (FF) and
light intensity (I) in organic
disordered-semiconductor-based solar cells is studied. An
analytical model describing the balance between transport
and recombination of charge carriers, parameterized with a
factor, Γm, is introduced to understand the FF-I relation,
where higher values of Γm correlate to larger FFs.
Comparing the effects of direct and tail-state-mediated
recombination on the FF-I plot, we find that, for
low-mobility systems, direct recombination with constant
transport mobility can deliver only a negative dependence of
Γm,dir on light intensity. By contrast, tail-state-mediated
recombination with trapping and detrapping processes can
produce a positive Γm,t versus sun dependency. The
analytical model is validated by numerical drift-diffusion
simulations. To further validate our model, two material
systems that show opposite FF-I behavior are studied:
poly{4,8-bis[5-(2-ethylhexyl)thiophen-2-yl]benzo[1,2-b;4,5-b′]dithiophene-2,6-diyl-alt-[4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene)-2-carboxylate-2-6-diyl]}
(PTB7-Th):[6,6]-phenyl-C71-butyric acid methyl ester
(PC71BM) devices show a negative FF-I relation, while
PTB7-Th:(5Z,5′Z)-5,5′-{[7,7′
-(4,4,9,9-tetraoctyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b′]dithiophene-2,7-diyl)bis(benzo[c][1,2,5]thiadiazole-7,4-diyl)]bis(methanylylidene)}bis(3-ethyl-2-thioxothiazolidin-4-one)
(O-IDTBR) devices show a positive correlation.
Optoelectronic measurements show that the O-IDTBR device
presents a higher ideality factor, stronger trapping and
detrapping behavior, and a higher density of trap states,
relative to the PC71BM device, supporting the theoretical
model. This work provides a comprehensive understanding of
the correlation between FF and light intensity for
disordered-semiconductor-based solar cells.},
cin = {IEK-5},
ddc = {530},
cid = {I:(DE-Juel1)IEK-5-20101013},
pnm = {121 - Solar cells of the next generation (POF3-121)},
pid = {G:(DE-HGF)POF3-121},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000560631000003},
doi = {10.1103/PhysRevApplied.14.024034},
url = {https://juser.fz-juelich.de/record/878470},
}