General method for simultaneous optimization of light trapping and carrier collection in an ultra-thin film organic photovoltaic cell

Journal Article · Mon Jul 14 00:00:00 EDT 2014 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4890275· OSTI ID:22308447

Tsai, Cheng-Chia; Grote, Richard R.; Beck, Jonathan H.; Kymissis, Ioannis ^[1]; Osgood, Richard M. ^[1]; Englund, Dirk ^[2]

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1. Department of Electrical Engineering, Columbia University, New York, New York 10027 (United States)
2. Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

We describe a general method for maximizing the short-circuit current in thin planar organic photovoltaic (OPV) heterojunction cells by simultaneous optimization of light absorption and carrier collection. Based on the experimentally obtained complex refractive indices of the OPV materials and the thickness-dependence of the internal quantum efficiency of the OPV active layer, we analyze the potential benefits of light trapping strategies for maximizing the overall power conversion efficiency of the cell. This approach provides a general strategy for optimizing the power conversion efficiency of a wide range of OPV structures. In particular, as an experimental trial system, the approach is applied here to a ultra-thin film solar cell with a SubPc/C{sub 60} photovoltaic structure. Using a patterned indium tin oxide (ITO) top contact, the numerically optimized designs achieve short-circuit currents of 0.790 and 0.980 mA/cm{sup 2} for 30 nm and 45 nm SubPc/C{sub 60} heterojunction layer thicknesses, respectively. These values correspond to a power conversion efficiency enhancement of 78% for the 30 nm thick cell, but only of 32% for a 45 nm thick cell, for which the overall photocurrent is actually higher. Applied to other material systems, the general optimization method can elucidate if light trapping strategies can improve a given cell architecture.

• OSTI ID: 22308447
• Journal Information: Journal of Applied Physics, Vol. 116, Issue 2; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ABSORPTION
CARRIERS
CONVERSION
ELECTRICAL FAULTS
FULLERENES
HETEROJUNCTIONS
INDIUM OXIDES
LAYERS
OPTIMIZATION
ORGANIC SEMICONDUCTORS
PHOTOVOLTAIC EFFECT
QUANTUM EFFICIENCY
REFRACTIVE INDEX
SOLAR CELLS
THICKNESS
THIN FILMS
TIN ADDITIONS
TRAPPING
VISIBLE RADIATION