scholarly journals Orientation dependent molecular electrostatics drives efficient charge generation in homojunction organic solar cells

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Yifan Dong ◽  
Vasileios C. Nikolis ◽  
Felix Talnack ◽  
Yi-Chun Chin ◽  
Johannes Benduhn ◽  
...  

Abstract Organic solar cells usually utilise a heterojunction between electron-donating (D) and electron-accepting (A) materials to split excitons into charges. However, the use of D-A blends intrinsically limits the photovoltage and introduces morphological instability. Here, we demonstrate that polycrystalline films of chemically identical molecules offer a promising alternative and show that photoexcitation of α-sexithiophene (α-6T) films results in efficient charge generation. This leads to α-6T based homojunction organic solar cells with an external quantum efficiency reaching up to 44% and an open-circuit voltage of 1.61 V. Morphological, photoemission, and modelling studies show that boundaries between α-6T crystalline domains with different orientations generate an electrostatic landscape with an interfacial energy offset of 0.4 eV, which promotes the formation of hybridised exciton/charge-transfer states at the interface, dissociating efficiently into free charges. Our findings open new avenues for organic solar cell design where material energetics are tuned through molecular electrostatic engineering and mesoscale structural control.

Author(s):  
Jie Lv ◽  
Hua Tang ◽  
Jiaming Huang ◽  
Cenqi Yan ◽  
Kuan Liu ◽  
...  

Due to the barrierless free charge generation, low charge trapping, and high charge mobilities, the PM6:Y6 organic solar cell (OSC) achieves excellent power conversion efficiency (PCE) of 15.7%. However, the...


Author(s):  
Mengyun Jiang ◽  
Hairui Bai ◽  
Hongfu Zhi ◽  
Lu Yan ◽  
Han Young Woo ◽  
...  

How to manipulate the phase separation and molecular arrangement to meet the need of efficient charge generation and extraction remains as the long-standing challenge in all-small-molecule organic solar cells (ASM-OSCs)....


Author(s):  
L. Benatto ◽  
C. A. M. Moraes ◽  
G. Candiotto ◽  
K. R. A. Sousa ◽  
J. P. A. Souza ◽  
...  

Our results provide a simple relationship involving the driving force and binding energy of CT state to maximize charge generation in non-fullerene organic solar cells.


2005 ◽  
Vol 20 (12) ◽  
pp. 3167-3179 ◽  
Author(s):  
Sophie E. Gledhill ◽  
Brian Scott ◽  
Brian A. Gregg

Organic photovoltaic devices are poised to fill the low-cost, low power niche in the solar cell market. Recently measured efficiencies of solid-state organic cells are nudging 5% while Grätzel’s more established dye-sensitized solar cell technology is more than double this. A fundamental understanding of the excitonic nature of organic materials is an essential backbone for device engineering. Bound electron-hole pairs, “excitons,” are formed in organic semiconductors on photo-absorption. In the organic solar cell, the exciton must diffuse to the donor–accepter interface for simultaneous charge generation and separation. This interface is critical as the concentration of charge carriers is high and recombination here is higher than in the bulk. Nanostructured engineering of the interface has been utilized to maximize organic materials properties, namely to compensate the poor exciton diffusion lengths and lower mobilities. Excitonic solar cells have different limitations on their open-circuit photo-voltages due to these high interfacial charge carrier concentrations, and their behavior cannot be interpreted as if they were conventional solar cells. This article briefly reviews some of the differences between excitonic organic solar cells and conventional inorganic solar cells and highlights some of the technical strategies used in this rapidly progressing field, whose ultimate aim is for organic solar cells to be a commercial reality.


2020 ◽  
Vol 4 (12) ◽  
pp. 6203-6211
Author(s):  
Yu Chen ◽  
Rui Cao ◽  
Hui Liu ◽  
M. L. Keshtov ◽  
Emmanuel N. Koukaras ◽  
...  

In order to increase the power conversion efficiency (PCE) of organic solar cells, developing high-performance non-fullerene small molecule acceptors is important for efficient charge generation and small energy loss.


Solar RRL ◽  
2020 ◽  
Vol 4 (4) ◽  
pp. 1900580 ◽  
Author(s):  
Yajie Zhang ◽  
Dan Deng ◽  
Qiong Wu ◽  
Yang Mi ◽  
Chen Yang ◽  
...  

Author(s):  
Yiwen Ji ◽  
Lingxia Xu ◽  
Hang Yin ◽  
Bin Cui ◽  
Longlong Zhang ◽  
...  

Organic solar cells (OSCs) based on nonfullerene acceptors (NFAs) have achieved rapid developments benefiting from the near-zero donor/acceptor (D/A) energy offset. However, a specific mechanism underlying the high-efficient charge generation...


Author(s):  
Zewen Chen ◽  
Hongzhu Chen ◽  
Chuang Feng ◽  
xiaojing wang ◽  
Zhicai He ◽  
...  

Efficient charge generation and transfer is crucial for Organic Solar Cells (OSCs) to achieve high power conversion efficiency (PCE). The ternary strategy is commonly used to expand the absorption range...


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