Concentrated sunlight for accelerated stability testing of organic photovoltaic materials: towards decoupling light intensity and temperature

Abstract

We have demonstrated OPV accelerated degradation studies using concentrated sunlight, where the atmosphere, temperature and illumination intensity were independently controlled. Testing various schemes for controlling the sample temperature under concentrated sunlight showed that heating of P3HT:PCBM was caused by photons at the absorbed wavelength range and dissipation of excess photon energy, and not necessarily by IR photon absorption. Sunlight chopping was found to be an effective method for independent temperature control under illumination by concentrated sunlight.The first accelerated degradation tests using sunlight concentration applied to P3HT:PCBM blends were reported. P3HT:PCBM blends exposed to concentrated sunlight in the presence of traces of oxygen/ humidity showed degradation induced by photo-oxidation of the P3HT backbone within the P3HT:PCBM blend, which is significantly thermally accelerated, in agreement with previous observations. However, this could be demonstrated in a time scale of 1 Corresponding authors2 minutes and hours, i.e., significantly accelerated. Exposure of well encapsulated P3HT:PCBM films to concentrated sunlight demonstrated stability up to 3,600 sun*hours, corresponding to about 1.6 years of operating time. This result was obtained at 300 suns exposure after merely 12 hours, demonstrating the advantage of using concentrated sunlight for accelerated stability tests.These tests can therefore combine extremely high acceleration factors with profound understanding of the effect of various, independently controlled factors on the degradation mechanisms.

Outdoor performance monitoring of perovskite solar cell mini-modules: Diurnal performance, observance of reversible degradation and variation with climatic performance

“…Temperature rise as a result of incident light can occur due to direct absorption from IR, thermalisation losses from other parts of the solar spectrum and absorption by contacts/encapsulants etc. Visoly-Fisher et al showed OPV devices can rise in temperature with exposure to sunlight even with the IR part of the spectrum omitted [30]. The figures for Ross coefficient are slightly lower than those obtained in previous experiments by this group on organic photovoltaic (OPV) modules (0.027 K m 2 /W) and polycrystalline (poly-Si) modules (0.028 K m 2 /W) [9].…”

Outdoor operation of small-molecule organic photovoltaics

“…At 27 suns intensity, approximately 800 W/m 2 [2] is converted to electrical power, depending on the currentvoltage operating point. The remaining absorbed power of >7 kW/m 2 is dissipated as heat through relaxation of high energy excitations, Joule heating, and absorption in the infrared [14]. Now the open-circuit voltage (V OC ) of the OPV is given by:…”

Effect of Halide Composition on the Photochemical Stability of Perovskite Photovoltaic Materials

“…We postulate that the introductiono fB ri nto the mixed halide solid solution stressed its structure and induced more structural defects and/org rain boundaries compared to pure halide perovskites, which might be responsible for the accelerated degradation. Accelerated stability tests [6] can rapidlys creen different PV materials and enhancet he development of stable and efficient devices. [1] The structure of such perovskites is AMX 3 ,w here Mi sad ivalent metal cation, Xa re halides, and Ai sa no rganic cation.…”

“…[3] Nohe tal. Accelerated stability tests [6] can rapidlys creen different PV materials and enhancet he development of stable and efficient devices. [4] Aharone tal.…”

“…[5] As ignificant challenge en route to commercializationo fp erovskite-based PV is the development of devicesc ombining high PCE and operational stability. Accelerated stability tests [6] can rapidlys creen different PV materials and enhancet he development of stable and efficient devices. Recently we demonstrateds uch an accelerated stability study of perovskite thin films using concentrated sunlight.…”