The role of donor-acceptor interfacial charge-transfer (CT) electronic states in photoelectric energy conversion in organic solar cells (Conference Presentation)

2019 ◽  
Author(s):  
Xiankai Chen
Keyword(s):  
Solar Cells ◽  
Charge Transfer ◽  
Energy Conversion ◽  
Organic Solar Cells ◽  
Electronic States ◽  
Interfacial Charge Transfer ◽  
Donor Acceptor ◽  
Interfacial Charge

scholarly journals Long-lived and disorder-free charge transfer states enable endothermic charge separation in efficient non-fullerene organic solar cells

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Ture F. Hinrichsen ◽  
Christopher C. S. Chan ◽  
Chao Ma ◽  
David Paleček ◽  
Alexander Gillett ◽  
...  
Keyword(s):  
Solar Cells ◽  
Charge Transfer ◽  
Organic Solar Cells ◽  
Charge Separation ◽  
Free Charge ◽  
Charge Generation ◽  
Time Resolved ◽  
Thermodynamic Conditions ◽  
Donor Acceptor ◽  
Interfacial Charge

Abstract Organic solar cells based on non-fullerene acceptors can show high charge generation yields despite near-zero donor–acceptor energy offsets to drive charge separation and overcome the mutual Coulomb attraction between electron and hole. Here, we use time-resolved optical spectroscopy to show that free charges in these systems are generated by thermally activated dissociation of interfacial charge-transfer states that occurs over hundreds of picoseconds at room temperature, three orders of magnitude slower than comparable fullerene-based systems. Upon free electron–hole encounters at later times, both charge-transfer states and emissive excitons are regenerated, thus setting up an equilibrium between excitons, charge-transfer states and free charges. Our results suggest that the formation of long-lived and disorder-free charge-transfer states in these systems enables them to operate closely to quasi-thermodynamic conditions with no requirement for energy offsets to drive interfacial charge separation and achieve suppressed non-radiative recombination.

Study of Interfacial Charge Transfer Loss in Hybrid Solar Cells by Impedance Spectroscopy

2015 ◽  
Vol 827 ◽  
pp. 162-167 ◽  
Author(s):  
Rahmat Hidayat ◽  
Yolla Sukma Handayani ◽  
Priastuti Wulandari
Keyword(s):  
Solar Cells ◽  
Charge Transfer ◽  
Impedance Spectroscopy ◽  
Organic Solar Cells ◽  
Transport Layer ◽  
Hybrid Solar Cells ◽  
Interfacial Charge Transfer ◽  
Metal Doped ◽  
Photovoltaic Characteristics ◽  
Interfacial Charge

Organic solar cells have been much studied because of the simplicity in their fabrication process in comparison to solar cells based on crystalline inorganic semiconductors. However, the actual power conversion efficiency is still much lower than the theoretical prediction, which may indicate the effect of inefficient charge transfer or charge recombination loss inside the cell. We have studied the photovoltaic characteristics of hybrid solar cells with transition metal doped ZnO layer as electron transport layers. Under dark condition, their J-V curves show a deviation from an ideal diode characteristic, which is indicated by current flow below the threshold voltage. Further investigations to clarify the photovoltaic characteristics of those cells were then carried out by the measurements of impedance spectroscopy. The impedance characteristics are dependent on the transport layer used, where the Nyquist plots of cells with TiZO exhibit larger impedance than those of cells with ZnO. However, those cells with larger impedance show better working performances. This fact was then interpreted as the result from smaller interfacial charge transfer loss, which may take place via charge carrier recombination at the interface of the transport layer and active layer, in the cells with TiZO.

Open-Circuit Voltage in Organic Solar Cells: The Impacts of Donor Semicrystallinity and Coexistence of Multiple Interfacial Charge-Transfer Bands

2017 ◽  
Vol 7 (12) ◽  
pp. 1601995 ◽  
Author(s):  
Guy O. Ngongang Ndjawa ◽  
Kenneth R. Graham ◽  
Sonya Mollinger ◽  
Di M. Wu ◽  
David Hanifi ◽  
...  
Keyword(s):  
Solar Cells ◽  
Charge Transfer ◽  
Organic Solar Cells ◽  
Open Circuit Voltage ◽  
Open Circuit ◽  
Interfacial Charge Transfer ◽  
Interfacial Charge

Uphill and downhill charge generation from charge transfer to charge separated states in organic solar cells

2021 ◽  
Author(s):  
Shahidul Alam ◽  
Vojtech Nádaždy ◽  
Tomáš Váry ◽  
Christian Friebe ◽  
Rico Meitzner ◽  
...  
Keyword(s):  
Cyclic Voltammetry ◽  
Solar Cells ◽  
Charge Transfer ◽  
Energy Level ◽  
Density Of States ◽  
Organic Solar Cells ◽  
Joint Density ◽  
Charge Generation ◽  
Donor Acceptor

Energy level alignments at the organic donor–acceptor interface cannot be predicted from cyclic voltammetry. Onsets for joint density of states and charge generation, reveal cases of energy uphill and – newly observed – downhill charge generation.

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