2012/03/27 by Daniel Rauh, D. Rauh, Carsten Deibel +3 · 1 citation
Chemistry · Engineering · Physics and Astronomy · #Charge (physics) #Charge carrier #Charge-carrier density #Fullerene Chemistry and Applications #Open-circuit voltage #Organic Electronics and Photovoltaics #Organic solar cell #Perovskite Materials and Applications #Phase (matter) #Polymer solar cell #Recombination #Trapping #cond-mat.mtrl-sci #cond-mat.soft
paper · pdf · doi:10.1002/adfm.201103118
published as Adv. Funct. Mater. 22, 3371 (2012) · 7 pages, 4 figures
arxiv created 2012/03/27 · openalex publication_date 2012/05/18 · arxiv updated 2012/08/23 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Abstract Apparent recombination orders exceeding the value of two expected for bimolecular recombination have been reported for organic solar cells in various publications. Two prominent explanations are bimolecular losses with a carrier concentration dependent prefactor due to a trapping limited mobility and protection of trapped charge carriers from recombination by a donor–acceptor phase separation until re‐emission from these deep states. In order to clarify which mechanism is dominant temperature‐ and illumination‐dependent charge extraction measurements are performed under open circuit and short circuit conditions at poly(3‐hexylthiophene‐2,5‐diyl):[6,6]‐phenyl‐C 61 butyric acid methyl ester (P3HT:PC 61 BM) and PTB7:PC 71 BM (poly[[4,8‐bis[(2‐ethylhexyl)oxy]benzo[1,2‐b:4,5‐b′]dithiophene‐2,6‐diyl][3‐fluoro‐2‐[(2‐ethylhexyl)carbonyl]thieno[3,4‐b]thiophenediyl]]) solar cells in combination with current–voltage characteristics. It is shown that the charge carrier density n dependence of the mobility μ and the recombination prefactor are different for P3HT:PC 61 BM at temperatures below 300 K and PTB7:PC 71 BM at room temperature. Therefore, in addition to μ ( n ), a detrapping limited recombination in systems with at least partial donor–acceptor phase separation is required to explain the high recombination orders.