Photodegradation of C‐PCPDTBT and Si‐PCPDTBT: Influence of the Bridging Atom on the Stability of a Low‐Band‐Gap Polymer for Solar Cell Application1. Issue 2 (10th November 2014)

• Record Type: Journal Article
• Authors: Aygül, Umut; Egelhaaf, Hans‐Joachim; Nagel, Peter; Merz, Michael; Schuppler, Stefan; Eichele, Klaus; Peisert, Heiko; Chassé, Thomas
• Is Part Of: Chemphyschem. Volume 16:Issue 2(2015)
• Page Start: 428
• Page End: 435
• Publication Date: 2014-11-10
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.05
• DOI: 10.1002/cphc.201402494
• Languages: English
• ISSNs: 1439-4235

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>The kinetics of photodegradation and the reactivity of different sites of the low‐band‐gap polymers poly[2, 6‐(4, 4‐<italic>bis</italic>‐(2‐ethylhexyl)‐4<italic>H</italic>‐cyclopenta[2, 1‐<italic>b</italic>:3, 4‐<italic>b</italic>′]dithiophene)‐<italic>alt</italic>‐4, 7‐(2, 1, 3‐benzothiadiazole)] (C‐PCPDTBT) and poly[2, 6‐(4, 4‐<italic>bis</italic>‐(2‐ethylhexyl)dithieno[3, 2‐<italic>b</italic>:2′, 3′‐<italic>d</italic>]silole)‐<italic>alt</italic>‐4, 7‐(2, 1, 3‐benzothiadiazole)] (Si‐PCPDTBT) are investigated as thin films and are compared to those of poly(3‐hexylthiophene) (P3HT). The decay kinetics are monitored with UV/Vis spectroscopy and the reactivity and product evolution are investigated with X‐ray photoelectron spectroscopy (XPS). Both polymers exhibit higher stability than P3HT. The bridging atom in the cyclopentadithiophene (CPDT) subunit has a significant influence on the stability. Varying oxidation rates for the different elements were observed. In the case of Si‐PCPDTBT, the silicon atom is oxidized primarily, whereas the photooxidation rates of the other elements are reduced relative to C‐PCPDTBT. Additionally, XPS experiments with varying excitation energies reveal a significant reaction gradient within a few nanometers of the surface of degraded thin films of C‐PCPDTBT.</p> </abstract>