Mobilities and lifetimes of photogenerated charge carriers are core properties of photovoltaic materials and can both be characterized by contactless terahertz or microwave measurements. Here, the expertise from fifteen laboratories is combined to quantitatively model the current‐voltage characteristics of a solar cell from such measurements. To this end, the impact of measurement conditions, alternate interpretations, and experimental inter‐laboratory variations are discussed using a (Cs,FA,MA)Pb(I,Br)3halide perovskite thin‐film as a case study. At 1 sun equivalent excitation, neither transport nor recombination is significantly affected by exciton formation or trapping. Terahertz, microwave, and photoluminescence transients for the neat material yield consistent effective lifetimes implying a resistance‐free JV‐curve with a potential power conversion efficiency of 24.6 %. For grainsizes above ≈20 nm, intra‐grain charge transport is characterized by terahertz sum mobilities of ≈32 cm2V−1s−1. Drift‐diffusion simulations indicate that these intra‐grain mobilities can slightly reduce the fill factor of perovskite solar cells to 0.82, in accordance with the best‐realized devices in the literature. Beyond perovskites, this work can guide a highly predictive characterization of any emerging semiconductor for photovoltaic or photoelectrochemical energy conversion. A best practice for the interpretation of terahertz and microwave measurements on photovoltaic materials is presented.
Photoluminescence Excitation Spectroscopy Characterization of Surface and Bulk Quality for Early-Stage Potential of Material Systems
Abstract — Photoluminescence Excitation Spectroscopy
(PLE) is a contactless characterization technique to quantify
Shockley-Reed-Hall (SRH) lifetimes and recombination velocities
in direct band gap experimental semiconductor materials and
devices. It is also useful as to evaluate surface passivation and
intermediate fabrication processes, since it can be implemented
without the need for development of effective contact technologies.
In this paper, we present a novel experimental PLE system for
precision-based quantification of the aforementioned parameters
as well as a system for which absolute PLE characterization may
occur. Absolute PLE measurements can be used to directly
calculate VOC for new photovoltaic (PV) material systems and
devices. Key system capabilities include a continuous excitation
spectrum from 300 nm –1.1 μm, automated characterization, up
to 1 nm wavelength resolution (up to 60x higher than prior work),
and a reduced ellipsometry requirement for post-processing of
data. We utilize a GaAs double heterostructure (DH) and an InP
crystalline wafer as calibration standards in comparison with data
from an LED-based PLE to demonstrate the validity of the results
obtained from this new system.
Index Terms – photovoltaic cells, photoluminescence, charge
carrier lifetime, gallium arsenide, indium phosphide.
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- Award ID(s):
- 1735282
- NSF-PAR ID:
- 10184483
- Date Published:
- Journal Name:
- Photoluminescence Excitation Spectroscopy Characterization of Surface and Bulk Quality for Early-Stage Potential of Material Systems
- Page Range / eLocation ID:
- 0377 to 0381
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1109/PVSC40753.2019.8980637
