Solution-processed small molecule:fullerene bulk-heterojunction solar cells: impedance spectroscopy deduced bulk and interfacial limits to fill-factors.
Using impedance spectroscopy, we demonstrate that the low fill factor (FF) typically observed in small molecule solar cells is due to hindered carrier transport through the active layer and hindered charge transfer through the anode interfacial layer (IFL). By carefully tuning the active layer thickness and anode IFL in BDT(TDPP)2 solar cells, the FF is increased from 33 to 55% and the PCE from 1.9 to 3.8%. These results underscore the importance of simultaneously optimizing active layer thickness and IFL in small molecule solar cells.
Photovoltaic and Optoelectronic Devices Group, Departament de Física, Universitat Jaume I, ES-12071 Castelló, Spain. bisquert@uji.es.
Antonio
A
Guerrero
Stephen
S
Loser
Germà
G
Garcia-Belmonte
Carson J
CJ
Bruns
Jeremy
J
Smith
Hiroyuki
H
Miyauchi
Samuel I
SI
Stupp
Juan
J
Bisquert
Tobin J
TJ
Marks
D058266:Dielectric Spectroscopy; D011211:Electric Power Supplies; D037741:Fullerenes / Q000737:chemistry*; D006575:Heterocyclic Compounds, 3-Ring / Q000737:chemistry*; D012993:Solar Energy; D012996:Solutions / Q000737:chemistry; D013876:Thiophenes / Q000737:chemistry*
D037741:Fullerenes; D006575:Heterocyclic Compounds, 3-Ring; D012996:Solutions; D013876:Thiophenes