Relationship between Work Function of Hole Collection Electrode and Temperature Dependence of Open-Circuit Voltage in Multilayered Organic Solar Cells

2012 ◽  
Vol 51 (2) ◽  
pp. 02BK14 ◽  
Author(s):  
Eiji Itoh ◽  
Toshiki Shirotori
Keyword(s):  
Solar Cells ◽  
Temperature Dependence ◽  
Work Function ◽  
Organic Solar Cells ◽  
Open Circuit Voltage ◽  
Open Circuit

scholarly journals Improving organic photovoltaic cells by forcing electrode work function well beyond onset of Ohmic transition

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Chao Zhao ◽  
Cindy G. Tang ◽  
Zong-Long Seah ◽  
Qi-Mian Koh ◽  
Lay-Lay Chua ◽  
...  
Keyword(s):  
Solar Cells ◽  
Fermi Level ◽  
Work Function ◽  
Organic Solar Cells ◽  
Carrier Mobility ◽  
Fill Factor ◽  
Open Circuit Voltage ◽  
Open Circuit ◽  
Fermi Level Pinning ◽  
Electrode Contact

AbstractAs electrode work function rises or falls sufficiently, the organic semiconductor/electrode contact reaches Fermi-level pinning, and then, few tenths of an electron-volt later, Ohmic transition. For organic solar cells, the resultant flattening of open-circuit voltage (Voc) and fill factor (FF) leads to a ‘plateau’ that maximizes power conversion efficiency (PCE). Here, we demonstrate this plateau in fact tilts slightly upwards. Thus, further driving of the electrode work function can continue to improve Voc and FF, albeit slowly. The first effect arises from the coercion of Fermi level up the semiconductor density-of-states in the case of ‘soft’ Fermi pinning, raising cell built-in potential. The second effect arises from the contact-induced enhancement of majority-carrier mobility. We exemplify these using PBDTTPD:PCBM solar cells, where PBDTTPD is a prototypal face-stacked semiconductor, and where work function of the hole collection layer is systematically ‘tuned’ from onset of Fermi-level pinning, through Ohmic transition, and well into the Ohmic regime.

Temperature dependence of HOMO-LUMO levels and open circuit voltage for P3HT:PCBM organic solar cells

2011 ◽  
Vol 1360 ◽  
Author(s):  
Yang Shen ◽  
Louis Scudiero ◽  
Mool C. Gupta
Keyword(s):  
Solar Cells ◽  
Energy Level ◽  
Temperature Dependence ◽  
Organic Solar Cells ◽  
Photoelectron Spectroscopy ◽  
Open Circuit Voltage ◽  
Bulk Heterojunction ◽  
Acid Methyl Ester ◽  
Open Circuit ◽  
Temperature Range

ABSTRACTIn this study, the open circuit voltage (VOC) of poly (3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM) bulk heterojunction (BHJ) organic solar cells was measured at temperatures ranging from 300 K to 400 K. The temperature dependence of the vacuum shift and of the highest occupied molecular orbital (HOMO) energy level of P3HT and PCBM were measured by ultraviolet photoelectron spectroscopy (UPS) in the same temperature range. The temperature dependence of the absorption edge was also studied in the same temperature range to obtain the temperature variation of the optical band gap energy (Eg). The measured VOC of the devices showed a clear decreasing trend with increasing operating temperature and the total decrease was found to be about 0.1 V. Although the origin of VOC is still not fully understood it is generally believed that the energy level offset between the HOMO of the donor and the LUMO of the acceptor minus the exciton binding energy (0.3 eV) directly determines the value of VOC. However, by utilizing the measured values of the HOMO for the P3HT (donor) and of the LUMO for the PCBM (acceptor), we have found that the calculated values of VOC and its temperature dependence do not agree with the measured VOC values. This indicates that factors other than the offset between the HOMO of the donor and the LUMO of the acceptor materials are impacting VOC.

Importance of interfacial crystallinity to reduce open-circuit voltage loss in organic solar cells

2019 ◽  
Vol 115 (15) ◽  
pp. 153301 ◽  
Author(s):  
Seiichiro Izawa ◽  
Naoto Shintaku ◽  
Mitsuru Kikuchi ◽  
Masahiro Hiramoto
Keyword(s):  
Solar Cells ◽  
Organic Solar Cells ◽  
Open Circuit Voltage ◽  
Open Circuit ◽  
Voltage Loss

scholarly journals Facile synthesis and photovoltaic applications of a new alkylated bismethano fullerene as electron acceptor for high open circuit voltage solar cells

RSC Advances ◽  
2015 ◽  
Vol 5 (79) ◽  
pp. 64724-64730 ◽  
Author(s):  
Derya Baran ◽  
Sule Erten-Ela ◽  
Andreas Kratzer ◽  
Tayebeh Ameri ◽  
Christoph J. Brabec ◽  
...  
Keyword(s):  
Solar Cells ◽  
Electron Acceptor ◽  
Organic Solar Cells ◽  
Open Circuit Voltage ◽  
Open Circuit ◽  
Facile Synthesis ◽  
Photovoltaic Applications ◽  
Lumo Level

In this work, a bis-adduct C60 derivative was facilely synthesized using an alkyl solubilizing group. This semiconductor offers a higher LUMO level compared to PCBM, which resulted in a significantly enhanced Voc of 0.73 V in organic solar cells.

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