Visualizing order in dispersions and solid state morphology with Cryo-TEM and electron tomography: P3HT : PCBM organic solar cells

Abstract

Document VersionPublisher's PDF, also known as Version of Record (includes final page, issue and volume numbers)Please check the document version of this publication:• A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. Link to publication• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Building blocks for organic solar cells are made from P3HT in a P3HT : PCBM solution in toluene and used to tune the morphology of the photoactive layer. The approach presented here decouples the structure and morphology formation, providing precise control over both the structures in solution and the morphology of the photoactive layer. For the characterization of the nanostructures in the organic casting solutions, cryo-TEM was successfully employed, and reveals the P3HT crystals and even the 1.7 nm lamellar stacking, which in combination with cryogenic low dose electron diffraction clearly proves the high crystallinity of P3HT aggregates realized. The photoactive layers made from pre-crystallized solutions show a morphology that is closely related to the structures in solution. A clear trend of decreasing open circuit voltage and increasing short circuit current with increasing order in the casting solutions and the devices was observed, which correlates with the evolution of the morphology from very intermixed with small fibrillar structures to phase-separated with large polymer crystals, as evaluated from representative devices, characterized in 3D with electron tomography.

Quantitative Analysis of Electron Beam Damage in Organic Thin Films

“…Therefore, to independently address the intensity of the PCBM peak at 0.217 Å –1 and the P3HT peak at 0.256 Å –1 , the spectrum was fitted to a model function by least-squares fitting. This function contains (in the same order as in eq 1) a Gaussian describing the PCBM peak, a Gaussian describing the P3HT peak, a Gaussian located between 0.285 and 0.323 Å –1 describing (inseparable) secondary components of both P3HT and PCBM, 28,31 a power law to estimate the inelastic background, and a constant representing residual dark current in the diffraction patterns. The variables a 1 and a 2 describe the intensity of the PCBM and P3HT signal, respectively.…”

Revealing the Side‐Chain‐Dependent Ordering Transition of Highly Crystalline Double‐Cable Conjugated Polymers

“…We then study the nanostructures of these double‐cable polymers by using TEM measurements. Cryo‐TEM was initially used to study biomacromolecules, and in recent years it was also applied into polymer materials [14] and even conjugated polymers [15] . For conjugated polymers, high‐energy electrons cause radiolysis which generates radicals, most likely from side‐chain scission.…”

“…We then study the nanostructures of these double-cable polymers by using TEM measurements.C ryo-TEM was initially used to study biomacromolecules,a nd in recent years it was also applied into polymer materials [14] and even conjugated polymers. [15] For conjugated polymers,h igh-energy electrons cause radiolysis which generates radicals,m ost likely from side-chain scission. These radicals diffuse around and destroy the crystal structure,r esulting in the loss of visibility of lattice fringes and diffraction rings with increasing electron dose.T EM observation at cryogenic temperatures has been shown to prevent the diffusion of radicals and increase the critical dose for damage-free TEM observation by an order of magnitude.F or these observations,t he dose was maintained at half the reported critical dose for conjugated polymers.…”

Исследование Структуры Объемного Гетероперехода В Полимерных Солнечных Элементах С Помощью Комбинации Ультрамикротомирования И Атомно-Силовой Микроскопии

“…Среди различных методов изучения наноструктуры фотоактивных слоев одними из наиболее широко приме-няемых методов являются атомно-силовая микроскопия (АСМ) и просвечивающая электронная микроскопия (ПЭМ) [5][6][7][8][9]. Два данных метода дают комплементар-ную информацию о наноструктуре образца, так как АСМ является методом для изучения поверхности и ПЭМ да-ет информацию о проекции объемной структуры.…”