TY - JOUR
T1 - Tail state limited photocurrent collection of thick photoactive layers in organic solar cells
AU - Wu, Jiaying
AU - Luke, Joel
AU - Lee, Harrison Ka Hin
AU - Shakya Tuladhar, Pabitra
AU - Cha, Hyojung
AU - Jang, Soo Young
AU - Tsoi, Wing Chung
AU - Heeney, Martin
AU - Kang, Hongkyu
AU - Lee, Kwanghee
AU - Kirchartz, Thomas
AU - Kim, Ji Seon
AU - Durrant, James R.
N1 - Generated from Scopus record by KAUST IRTS on 2023-02-14
PY - 2019/12/1
Y1 - 2019/12/1
N2 - We analyse organic solar cells with four different photoactive blends exhibiting differing dependencies of short-circuit current upon photoactive layer thickness. These blends and devices are analysed by transient optoelectronic techniques of carrier kinetics and densities, air photoemission spectroscopy of material energetics, Kelvin probe measurements of work function, Mott-Schottky analyses of apparent doping density and by device modelling. We conclude that, for the device series studied, the photocurrent loss with thick active layers is primarily associated with the accumulation of photo-generated charge carriers in intra-bandgap tail states. This charge accumulation screens the device internal electrical field, preventing efficient charge collection. Purification of one studied donor polymer is observed to reduce tail state distribution and density and increase the maximal photoactive thickness for efficient operation. Our work suggests that selecting organic photoactive layers with a narrow distribution of tail states is a key requirement for the fabrication of efficient, high photocurrent, thick organic solar cells.
AB - We analyse organic solar cells with four different photoactive blends exhibiting differing dependencies of short-circuit current upon photoactive layer thickness. These blends and devices are analysed by transient optoelectronic techniques of carrier kinetics and densities, air photoemission spectroscopy of material energetics, Kelvin probe measurements of work function, Mott-Schottky analyses of apparent doping density and by device modelling. We conclude that, for the device series studied, the photocurrent loss with thick active layers is primarily associated with the accumulation of photo-generated charge carriers in intra-bandgap tail states. This charge accumulation screens the device internal electrical field, preventing efficient charge collection. Purification of one studied donor polymer is observed to reduce tail state distribution and density and increase the maximal photoactive thickness for efficient operation. Our work suggests that selecting organic photoactive layers with a narrow distribution of tail states is a key requirement for the fabrication of efficient, high photocurrent, thick organic solar cells.
UR - https://www.nature.com/articles/s41467-019-12951-7
UR - http://www.scopus.com/inward/record.url?scp=85075063161&partnerID=8YFLogxK
U2 - 10.1038/s41467-019-12951-7
DO - 10.1038/s41467-019-12951-7
M3 - Article
SN - 2041-1723
VL - 10
JO - Nature Communications
JF - Nature Communications
IS - 1
ER -