Fast and Nondestructive Failure Analysis of Organic Photovoltaic Modules for Low‐Light Harvesting: Coupling Variable Illumination Measurements to Electroluminescence Imaging

Abstract

Today, organic photovoltaics (OPV) have reached a maturity level compatible with market deployment. As this technology surpasses traditional solar devices when illuminated by artificial light sources (producing low irradiance), indoor light harvesting represents one of the most relevant application for OPV modules. However, there is a lack of methods to detect defective modules dedicated to such applications. At the single-cell level, it is already established that parallel resistance stands for a figure-of-merit for low-light performance. However, its influence in the case of a series-connected OPV module has not been described yet. Herein, it is reported how parallel resistance discrepancies from cell to cell within an OPV module dramatically affect module performance. Thanks to onediode modeling, parallel resistance threshold values can be determined for each cell, for a targeted light intensity. In addition, defective cells can be localized by electroluminescence imaging. The usefulness and applicability of the proposed approach is demonstrated on 4-cell and 9-cell modules printed on an industrial tool.

ITO‐Free Indoor OPV Modules from Nonhalogenated Solvents

“…On module level, a (partially) shunted cell will reduce the device's FF and voltage without showing a prominent slope in the dark current. For module fabrication, the shunt control has to be done by luminescence [ 30 ] or thermography. [ 33 ] Figure 5a shows the data of a batch of nine substrates with similar 0.1 cm 2 solar cells, it represents thereby a random spatial probing of the area, since each substrate has a size of 2.5 × 2.5 cm 2 and contains six individual solar cells.…”

“…The importance of a high parallel resistance (R P ) for a good solar cell performance under low intensity illumination was already discussed elsewhere. [5,[28][29][30][31] Different groups stated different absolute values, for example, Steim et al published 85 kΩcm 2 as a minimum requirement for the R P not to be limiting under a cw-fluorescent lamp (light color 830) at 1000 lux. [5] Proctor et al argued for R P values greater than 1 M Ω cm 2 for light intensities less than 1 sun.…”