TY  - JOUR
A1  - Pranav, Manasi
A1  - Benduhn, Johannes
A1  - Nyman, Mathias
A1  - Hosseini, Seyed Mehrdad
A1  - Kublitski, Jonas
A1  - Shoaee, Safa
A1  - Neher, Dieter
A1  - Leo, Karl
A1  - Spoltore, Donato
T1  - Enhanced charge selectivity via anodic-C60 layer reduces nonradiative losses in organic solar cells
JF  - ACS applied materials & interfaces
N2  - Interfacial layers in conjunction with suitable charge-transport layers can significantly improve the performance of optoelectronic devices by facilitating efficient charge carrier injection and extraction. 
This work uses a neat C-60 interlayer on the anode to experimentally reveal that surface recombination is a significant contributor to nonradiative recombination losses in organic solar cells. 
These losses are shown to proportionally increase with the extent of contact between donor molecules in the photoactive layer and a molybdenum oxide (MoO3) hole extraction layer, proven by calculating voltage losses in low- and high-donor-content bulk heterojunction device architectures. 
Using a novel in-device determination of the built-in voltage, the suppression of surface recombination, due to the insertion of a thin anodic-C-60 interlayer on MoO3, is attributed to an enhanced built-in potential. 
The increased built-in voltage reduces the presence of minority charge carriers at the electrodes-a new perspective on the principle of selective charge extraction layers. 
The benefit to device efficiency is limited by a critical interlayer thickness, which depends on the donor material in bilayer devices. 
Given the high popularity of MoO3 as an efficient hole extraction and injection layer and the increasingly popular discussion on interfacial phenomena in organic optoelectronic devices, these findings are relevant to and address different branches of organic electronics, providing insights for future device design.
KW  - nonradiative losses
KW  - molybdenum oxide
KW  - organic solar cells
KW  - interfacial layers
KW  - charge selectivity
Y1  - 2021
U6  - https://doi.org/10.1021/acsami.1c00049
SN  - 1944-8244
SN  - 1944-8252
VL  - 13
IS  - 10
SP  - 12603
EP  - 12609
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Pranav, Manasi
A1  - Hultzsch, Thomas
A1  - Musiienko, Artem
A1  - Sun, Bowen
A1  - Shukla, Atul
A1  - Jaiser, Frank
A1  - Shoaee, Safa
A1  - Neher, Dieter
T1  - Anticorrelated photoluminescence and free charge generation proves field-assisted exciton dissociation in low-offset PM6:Y5 organic solar cells
JF  - APL materials : high impact open access journal in functional materials science
N2  - Understanding the origin of inefficient photocurrent generation in organic solar cells with low energy offset remains key to realizing high-performance donor-acceptor systems. Here, we probe the origin of field-dependent free-charge generation and photoluminescence in wnon-fullereneacceptor (NFA)-based organic solar cells using the polymer PM6 and the NFA Y5-a non-halogenated sibling to Y6, with a smaller energetic offset to PM6. By performing time-delayed collection field (TDCF) measurements on a variety of samples with different electron transport layers and active layer thickness, we show that the fill factor and photocurrent are limited by field-dependent free charge generation in the bulk of the blend. We also introduce a new method of TDCF called m-TDCF to prove the absence of artifacts from non-geminate recombination of photogenerated and dark charge carriers near the electrodes. We then correlate free charge generation with steady-state photoluminescence intensity and find perfect anticorrelation between these two properties. Through this, we conclude that photocurrent generation in this low-offset system is entirely controlled by the field-dependent dissociation of local excitons into charge-transfer states. (c) 2023 Author(s).
Y1  - 2023
U6  - https://doi.org/10.1063/5.0151580
SN  - 2166-532X
VL  - 11
IS  - 6
PB  - AIP Publishing
CY  - Melville
ER  -