Thermally induced degradation of PBDTTT-CT:PCBM based polymer solar cells

Abstract

Thermally induced degradation of photovoltaic performance in bulk-heterojunction (BHJ) polymer solar cells as a result of changes either in the active layer morphology or at interfaces during operation at elevated temperature is a common phenomenon. In this work, we have studied the thermal stability of a high performance polymer:fullerene BHJ PSCcomprising a conjugated polymer poly{[4,8-bis-(2-ethyl-hexyl-thiophene-5-yl)-benzo[1,2-b:4,5-b0]dithiophene-2,6-diyl]-alt-[2-(20-ethyl-hexanoyl)-thieno[3,4-b]thiophen-4,6-diyl]} (PBDTTT-CT) and a fullerene derivative [6,6]-phenyl-C70-butyric acid methyl ester photoactive layer within a conventional device architecture of glass/ITO/PEDOT:PSS/active layer/Mg/Al. By varying the temperature exposure conditions, the degradation path has been identified as an interfacial change in the device rather than a bulk effect. Furthermore, charge carrier dynamics studied by open circuit corrected charge carrier extraction has shown that post-annealed devices suffer from charge extraction due to the development of interfacial changes as compared to the non-treated devices in both pristine and with 1,8-Diiodooctane added scenarios.

Compatible Solution‐Processed Interface Materials for Improved Efficiency of Polymer Solar Cells

“…Even with high work function magnesium as the electron transport layer, the V oc of PBDTTT‐C‐T:PC 71 BM‐based OSCs remains stable under continuous irradiation at 45 and 65 °C. [ 26 ] Because of this, all three ETL‐interlayers did not show a different impact on the V oc stability, even though the material system largely differs. However, after 1000 h of continuous illumination at 45 °C, the PCE of all devices had fallen to less than 60% of the initial PCE, which is reflected by the decreases of J sc , FF, and R p already, as well as the increase in R s .…”

Recent Advances and Opportunities for Cellulose Nanocrystal-Based Liquid Crystalline Polymer Hybrids and Composite Materials

“…The cholesteric domains in lyotropic and thermotropic CNCs present 1D photonic features for optically active smart materials, 140,141 OLEDs, 142 and solar cells. 139,143 There are several issues that need to be addressed when using CNC hybrid materials as an environmentally friendly alternative to synthetic LCPs. These include (i) the development of green chemistry methods to synthesize the CNC-LC platform, (ii) the use of LC and LCPs that are water or ionic liquid soluble, degradable/recyclable/compostable, and from sustainable sources, (iii) scalability and cost of synthesis and processing methods, and (iv) stability and degradability/recyclability/ compostability of these materials after use.…”

Metallophthalocyanines in a ternary photoactive layer (P3HT:MPc:PC70BM) for bulk heterojunction solar cells

“…Device instability can occur due to an array of complex phenomena that take place at any of the layers and/ or interfacial layers such as the diffusion of oxygen and water, 63 oxidation and eventual rusting of metal electrodes 64 and thermal and photoinduced degradation of the active layer. 65 Despite the relatively consistent PCE output from the nine BHJ devices over the seven days, longer testing times should be considered to gain a holistic outlook of any potential threats to device stability. In the wake of extensive perovskite solar cell (PSC) research directed towards tackling stability issues, even though the PCEs obtained from PSCs are often comparatively higher than OPV cells, the stability of these BHJ cells at ambient conditions are favourable when compared to the stability of PSC devices developed in recent studies.…”