Role of Morphology and Förster Resonance Energy Transfer in Non-fullerene Acceptor based Ternary Blend Organic Solar Cells
Aiswarya Abhisek Mohapatra a, Ravichandran Shivanna b, Suresh Podapangi a, Alexander Hinderhofer c, M. Ibrahim Dar b, Frank Schreiber c, Aditya Sadhanala a b d, Richard H. Friend b, Satish Patil a
a Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore, India
b Cavendish Laboratory, Department of Physics, University of Cambridge, UK, JJ Thomson Avenue, Cambridge, United Kingdom
c Institut für Angewandte Physik, Universität Tübingen, Germany, Tübingen, Germany
d Clarendon Laboratory, Department of Physics, Oxford University, Oxford OX1 3PU, UK
Proceedings of Online International Conference on Hybrid and Organic Photovoltaics (OnlineHOPV20)
Online, Spain, 2020 May 26th - 29th
Organizers: Tracey Clarke, James Durrant, Annamaria Petrozza and Trystan Watson
Poster, Aiswarya Abhisek Mohapatra, 132
Publication date: 22nd May 2020
ePoster: 

Organic solar cells (OSCs) fabricated from ternary blend thin film absorbers are designed to maximize the range of absorption in solar spectrum, and thus increase the short-circuit current (JSC) of the device. However, the detailed origin of improved JSC in ternary blend solar cells (TBSC) still lacks explicit illustration. Therefore, understanding the origin of high Jsc and identifying rational approach are of great importance. In this work, we have fabricated OSCs by mixing two different compositions of ternary blend thin films namely; PTB7-Th/PCDTBT/IT4F and PTB7-Th/PBDB-T/IT4F. The role of excited-state electronic processes and thin film morphology for tuneable photocurrent and voltage losses are identified and discussed in the framework of Förster resonance energy transfer (FRET). We observed ≥ 10% increment in JSC for both the ternary blends, which enhanced power conversion efficiency (PCE) up to 10.34% for PTB7-Th:PBDB-T:IT4F blend. We provide evidence that the two foremost parameters controlling the PCE are blend morphology and FRET between donor components. Both the polymers formed a homogeneous phase with PTB7-Th which was evident from the tuneable open-circuit voltage (VOC) of the ternary blends with varying donor composition. Physical incompatibility of PCDTBT with IT4F limited its amount in the optimized PTB7-Th:PCDTBT:IT4F blend (5% with respect to PTB7-Th), therefore limiting the effect of FRET on device photocurrent. Whereas, PBDB-T, owing to better physical compatibility with IT4F resulted a composition-tolerant ternary blend system.

ØS.P. thanks Indo-UK SUNRISE program for funding.

ØA.A.M. thanks Indian Institute of Science for senior research fellowship.

ØR.H.F. acknowledges the support from EPSRC and Indo-UK SUNRISE project

ØA.H. and F.S. acknowledge DESY (Hamburg, Germany) for the provision of experimental facilities at PETRA III and we would like to thank Florian Bertram for assistance in using beamline P08.

ØM.I.D acknowledges the financial support from the Swiss National Science Foundation under the project number P300P2_174471.

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