skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Microlens array induced light absorption enhancement in polymer solar cells

Abstract

Over the last decade, polymer solar cells (PSCs) have attracted a lot of attention and highest power conversion efficiencies (PCE) are now close to 10%. Here we employ an optical structure – the microlens array (MLA) – to increase light absorption inside the active layer, and PCE of PSCs increased even for optimized devices. Normal incident light rays are refracted at the MLA and travel longer optical paths inside the active layers. Two PSC systems – poly(3-hexylthiophene-2,5-diyl):(6,6)-phenyl C61 butyric acid methyl ester (P3HT:PCBM) and poly[[9-(1-octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl]:(6,6)-phenyl C71 butyric acid methyl ester (PCDTBT:PC70BM) – were investigated. In the P3HT:PCBM system, MLA increased the absorption, absolute external quantum efficiency, and the PCE of an optimized device by [similar]4.3%. In the PCDTBT:PC70BM system, MLA increased the absorption, absolute external quantum efficiency, and PCE by more than 10%. In addition, simulations incorporating optical parameters of all structural layers were performed and they support the enhancement of absorption in the active layer with the assistance of MLA. Our results show that utilizing MLA is an effective strategy to further increase light absorption in PSCs, in which optical losses account for [similar]40% of total losses. MLA also does not pose materials processing challenges to the active layersmore » since it is on the other side of the transparent substrate.« less

Authors:
 [1];  [2];  [1];  [1];  [2];  [1];  [1]
  1. Ames Laboratory
  2. Iowa State University
Publication Date:
Research Org.:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1082681
Report Number(s):
IS-J 7953
DOE Contract Number:
DE-AC02-07CH11358
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Chemistry Chemical Physics; Journal Volume: 2013; Journal Issue: 12
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY

Citation Formats

Chen, Yuqing, Elshobaki, Moneim, Ye, Zhuo, Park, Joong-Mok, Noack, Max A., Ho, Kai-Ming, and Chaudhary, Sumit. Microlens array induced light absorption enhancement in polymer solar cells. United States: N. p., 2013. Web. doi:10.1039/C3CP50297J.
Chen, Yuqing, Elshobaki, Moneim, Ye, Zhuo, Park, Joong-Mok, Noack, Max A., Ho, Kai-Ming, & Chaudhary, Sumit. Microlens array induced light absorption enhancement in polymer solar cells. United States. doi:10.1039/C3CP50297J.
Chen, Yuqing, Elshobaki, Moneim, Ye, Zhuo, Park, Joong-Mok, Noack, Max A., Ho, Kai-Ming, and Chaudhary, Sumit. Thu . "Microlens array induced light absorption enhancement in polymer solar cells". United States. doi:10.1039/C3CP50297J.
@article{osti_1082681,
title = {Microlens array induced light absorption enhancement in polymer solar cells},
author = {Chen, Yuqing and Elshobaki, Moneim and Ye, Zhuo and Park, Joong-Mok and Noack, Max A. and Ho, Kai-Ming and Chaudhary, Sumit},
abstractNote = {Over the last decade, polymer solar cells (PSCs) have attracted a lot of attention and highest power conversion efficiencies (PCE) are now close to 10%. Here we employ an optical structure – the microlens array (MLA) – to increase light absorption inside the active layer, and PCE of PSCs increased even for optimized devices. Normal incident light rays are refracted at the MLA and travel longer optical paths inside the active layers. Two PSC systems – poly(3-hexylthiophene-2,5-diyl):(6,6)-phenyl C61 butyric acid methyl ester (P3HT:PCBM) and poly[[9-(1-octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl]:(6,6)-phenyl C71 butyric acid methyl ester (PCDTBT:PC70BM) – were investigated. In the P3HT:PCBM system, MLA increased the absorption, absolute external quantum efficiency, and the PCE of an optimized device by [similar]4.3%. In the PCDTBT:PC70BM system, MLA increased the absorption, absolute external quantum efficiency, and PCE by more than 10%. In addition, simulations incorporating optical parameters of all structural layers were performed and they support the enhancement of absorption in the active layer with the assistance of MLA. Our results show that utilizing MLA is an effective strategy to further increase light absorption in PSCs, in which optical losses account for [similar]40% of total losses. MLA also does not pose materials processing challenges to the active layers since it is on the other side of the transparent substrate.},
doi = {10.1039/C3CP50297J},
journal = {Physical Chemistry Chemical Physics},
number = 12,
volume = 2013,
place = {United States},
year = {Thu Jan 24 00:00:00 EST 2013},
month = {Thu Jan 24 00:00:00 EST 2013}
}
  • Here, we demonstrate enhanced absorption in solar cells and enhanced light emission in OLEDs by light interaction with a periodically structured microlens array. We simulate n-i-p perovskite solar cells with a microlens at the air-glass interface, with rigorous scattering matrix simulations. The microlens focuses light in nanoscale regions within the absorber layer enhancing the solar cell. Optimal period of ~700 nm and microlens height of ~800-1000 nm, provides absorption (photocurrent) enhancement of 6% (6.3%). An external polymer microlens array on the air-glass side of the OLED generates experimental and theoretical enhancements >100%, by outcoupling trapped modes in the glass substrate.
  • A novel approach to increasing light absorption in thin-film solar cells is demonstrated. This new method involves redirecting the incident sunlight into the cell via coupling to the whispering gallery modes of dielectric spheres, which lie atop the cell. Such a scheme leads to a predicted current enhancement of >12% for a-Si.
  • We have investigated the effects induced by periodic nanosphere arrays on the performance of organic solar cells (OSCs). Two-dimensional periodic arrays of polystyrene nanospheres were formed by using a colloidal lithography method together with plasma etching to trim down the size to various degrees on the substrates of OSCs. It is found that the devices prepared on such substrates can have improved light harvesting, resulting in as high as 35% enhancement in power conversion efficiency over that of the reference devices. The measured external quantum efficiency and finite-difference time-domain simulation reveal that the controlled periodic morphology of the substrate canmore » efficiently increase light scattering in the device and thus enhance the absorption of incident light.« less
  • The nature of light- and current-induced metastabilities under electrical bias in hydrogenated nanocrystalline silicon (nc-Si:H) solar cells has been found to be different from those in hydrogenated amorphous silicon (a-Si:H)-based solar cells. First, a forward-bias current injection in the dark does not cause any degradation in nc-Si:H cell performance. The phenomenon is explained by the percolation transport through crystalline paths, where the excess carrier recombination does not cause degradation. Second, a reverse bias does not reduce, but enhances the light-induced degradation in the nc-Si:H cell performance. The enhancement increases with the magnitude of the applied reverse bias. By measuring themore » quantum efficiency losses and color (blue, wavelength=390 nm and red, wavelength=670 nm) fill factors, we suggest that the reverse-bias-enhanced defect generation mostly takes place in the grain-boundary regions. Light-soaking experiments using light with different spectra show that a reverse bias under white light causes more enhancement in the degradation than under blue light (wavelength shorter than 650 nm). No degradation occurs under red light (wavelength longer than 665 nm) in either open-circuit or reverse-bias condition. A ''back-to-back'' diode model is proposed to explain these phenomena in terms of the heterogeneity of the material structure.« less