Neutron Radiation Tolerance of Two Benchmark Thiophene-Based Conjugated Polymers: the Importance of Crystallinity for Organic Avionics

Abstract

Aviation and space applications can benefit significantly from lightweight organic electronics, now spanning from displays to logics, because of the vital importance of minimising payload (size and mass). It is thus crucial to assess the damage caused to such materials by cosmic rays and neutrons, which pose a variety of hazards through atomic displacements following neutron-nucleus collisions. Here we report the first study of the neutron radiation tolerance of two poly(thiophene)s-based organic semiconductors: poly(3-hexylthiophene-2,5-diyl), P3HT, and the liquid-crystalline poly(2,5-bis (3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene), PBTTT. We combine spectroscopic investigations with characterisation of intrinsic charge mobility to show that PBTTT exhibits significantly higher tolerance than P3HT. We explain this in terms of a superior chemical, structural and conformational stability of PBTTT, which can be ascribed to its higher crystallinity, in turn induced by a combination of molecular design features. Our approach can be used to develop design strategies for better neutron radiation-tolerant materials, thus paving the way for organic semiconductors to enter avionics and space applications.

Perovskite solar cell resilience to fast neutrons

“…14 For these reasons, neutrons are not only employed for gaining spectroscopic and structural information, 20,21 but also for assessing the resilience of electronics in harsh radiation environments. 22,23 Here, we extend our previous studies on neutron irradiation of organic electronics 23 to perovskite-based PVs. The analysis of the electric PV characteristics either under light illumination (control device) or upon the combined action of light and fast neutrons highlights the irreversible nature of the neutroninduced effects, in stark contrast with the fully reversible photoinduced degradation.…”

“…1). 23 At a normal primary proton current (180 mA h À1 ) the integrated fast neutron (>10 MeV) ux was determined 26 to be approximately 6 Â 10 4 n cm À2 s À1 whereas the estimated fast neutron uence received by the ISS is z0.6 n cm À2 s À1 (Fig. 1), 14 meaning that 1 h of irradiation corresponds to z10 years of exposure on the ISS.…”

Twist and Degrade—Impact of Molecular Structure on the Photostability of Nonfullerene Acceptors and Their Photovoltaic Blends

“…After 8 h of degradation of the neat and blend films, the main P3HT CC peak broadens to lower frequencies and there is an increase in relative intensity of the CC peak at ≈1200 cm −1 . [51,52] Note that the Raman features and deeper HOMO appearing in photo-oxidized samples also have a close resemblance with polaronic species formed upon chemical doping of P3HT. The Raman simulations of the P3HT pentamer containing a sulfoxide unit show similarities to those of the experimentally degraded P3HT ( Figure S22, Supporting Information), thus providing a possible origin to these observations; these spectral changes have been previously observed upon P3HT degradation in air.…”

Organic and perovskite solar cells for space applications

“…The ISOS standards [12] applied in the HOPV community are thus not sufficient to validate the degradation induced by space-related stress factors. For this reason, a few groups already started investigating the effects of high energy proton irradiation, with promising results both for allorganic [13][14][15] and for perovskite [16] devices. Reports on the degradation induced by wide and quickly varying temperature ranges are still missing, although insights into the effects of low operating temperatures are available from studies conducted for different aims [17].…”