Abstract
There is mounting evidence that long-range charge separation determines the efficiency of organic photovoltaic cells, yet different mechanisms remain under debate. One class of proposed mechanism is ultrafast coherent long-range charge separation, and another is a slower process whereby charges incoherently hop apart with a transiently enhanced mobility due to morphology and disorder. Here, we use transient absorption spectroscopy to probe incoherent charge separation dynamics in two different ways. First, we use a family of polymers whose backbone structures allows us to compare 2- phase donor-acceptor morphologies with 3-phase morphologies that feature an intermixed region. In the 3-phase system, we see pronounced spectral signatures associated with charges (holes) occupying the disordered intermixed region, and we track separation via biased charge diffusion to more ordered neat regions on the timescale of hundreds of picoseconds. Secondly, by resolving bimolecular charge recombination at high excitation density, we show that charge mobilities must be substantially enhanced on early timescales, which may be sufficient for separation to occur. Together, these measurements provide support for models of incoherent and relatively slow charge separation.
| Original language | English |
|---|---|
| Title of host publication | Physical Chemistry of Interfaces and Nanomaterials XV |
| Editors | Robert Lovrincic, Artem A. Bakulin, Natalie Banerji |
| Publisher | SPIE |
| ISBN (Electronic) | 9781510602373 |
| DOIs | |
| Publication status | Published - 2016 Jan 1 |
| Event | Physical Chemistry of Interfaces and Nanomaterials XV - San Diego, United States Duration: 2016 Aug 28 → 2016 Aug 31 |
Publication series
| Name | Proceedings of SPIE - The International Society for Optical Engineering |
|---|---|
| Volume | 9923 |
| ISSN (Print) | 0277-786X |
| ISSN (Electronic) | 1996-756X |
Conference
| Conference | Physical Chemistry of Interfaces and Nanomaterials XV |
|---|---|
| Country | United States |
| City | San Diego |
| Period | 16/8/28 → 16/8/31 |
Fingerprint
Keywords
- Charge separation
- Intermixed phase
- Mobility relaxation
- Organic photovoltaic
- Three phase
- Transient absorption
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Computer Science Applications
- Applied Mathematics
- Electrical and Electronic Engineering
Cite this
Incoherent charge separation dynamics in organic photovoltaics. / Prasad, Shyamal K.K.; Gallaher, Joseph K.; Barker, Alex J.; Woo, Han Young; Abbas, Mamatimin; Hirsch, Lionel; Hodgkiss, Justin M.
Physical Chemistry of Interfaces and Nanomaterials XV. ed. / Robert Lovrincic; Artem A. Bakulin; Natalie Banerji. SPIE, 2016. 99231F (Proceedings of SPIE - The International Society for Optical Engineering; Vol. 9923).Research output: Chapter in Book/Report/Conference proceeding › Conference contribution
}
TY - GEN
T1 - Incoherent charge separation dynamics in organic photovoltaics
AU - Prasad, Shyamal K.K.
AU - Gallaher, Joseph K.
AU - Barker, Alex J.
AU - Woo, Han Young
AU - Abbas, Mamatimin
AU - Hirsch, Lionel
AU - Hodgkiss, Justin M.
PY - 2016/1/1
Y1 - 2016/1/1
N2 - There is mounting evidence that long-range charge separation determines the efficiency of organic photovoltaic cells, yet different mechanisms remain under debate. One class of proposed mechanism is ultrafast coherent long-range charge separation, and another is a slower process whereby charges incoherently hop apart with a transiently enhanced mobility due to morphology and disorder. Here, we use transient absorption spectroscopy to probe incoherent charge separation dynamics in two different ways. First, we use a family of polymers whose backbone structures allows us to compare 2- phase donor-acceptor morphologies with 3-phase morphologies that feature an intermixed region. In the 3-phase system, we see pronounced spectral signatures associated with charges (holes) occupying the disordered intermixed region, and we track separation via biased charge diffusion to more ordered neat regions on the timescale of hundreds of picoseconds. Secondly, by resolving bimolecular charge recombination at high excitation density, we show that charge mobilities must be substantially enhanced on early timescales, which may be sufficient for separation to occur. Together, these measurements provide support for models of incoherent and relatively slow charge separation.
AB - There is mounting evidence that long-range charge separation determines the efficiency of organic photovoltaic cells, yet different mechanisms remain under debate. One class of proposed mechanism is ultrafast coherent long-range charge separation, and another is a slower process whereby charges incoherently hop apart with a transiently enhanced mobility due to morphology and disorder. Here, we use transient absorption spectroscopy to probe incoherent charge separation dynamics in two different ways. First, we use a family of polymers whose backbone structures allows us to compare 2- phase donor-acceptor morphologies with 3-phase morphologies that feature an intermixed region. In the 3-phase system, we see pronounced spectral signatures associated with charges (holes) occupying the disordered intermixed region, and we track separation via biased charge diffusion to more ordered neat regions on the timescale of hundreds of picoseconds. Secondly, by resolving bimolecular charge recombination at high excitation density, we show that charge mobilities must be substantially enhanced on early timescales, which may be sufficient for separation to occur. Together, these measurements provide support for models of incoherent and relatively slow charge separation.
KW - Charge separation
KW - Intermixed phase
KW - Mobility relaxation
KW - Organic photovoltaic
KW - Three phase
KW - Transient absorption
UR - http://www.scopus.com/inward/record.url?scp=85008313645&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85008313645&partnerID=8YFLogxK
U2 - 10.1117/12.2238234
DO - 10.1117/12.2238234
M3 - Conference contribution
AN - SCOPUS:85008313645
T3 - Proceedings of SPIE - The International Society for Optical Engineering
BT - Physical Chemistry of Interfaces and Nanomaterials XV
A2 - Lovrincic, Robert
A2 - Bakulin, Artem A.
A2 - Banerji, Natalie
PB - SPIE
ER -