Integrated molecular, morphological and interfacial engineering towards highly efficient and stable solution-processed small molecule solar cells

Abstract

and recombination loss mechanisms for these oligomers. This study not only revealed the importance of integrated alkyl chain engineering on gaining morphological control for high performance OSCs, but also exhibited a clear correlation between molecular ordering and charge carrier mobility respective to carrier dynamics. These results outline a detailed strategy towards a rather complete characterization and optimization methodology for organic photovoltaic devices, thereby paving the way for researchers to easily find the performance parameters adapted for widespread applications.

Side‐Chain Engineering for Enhancing the Properties of Small Molecule Solar Cells: A Trade‐off Beyond Efficiency

“…Thus, the ratio between the bimolecular recombination coefficient and the Langevin recombination coefficient (β/β L ) in BDTT-S-TR system is approximately one order of magnitude lower than that of the other two systems. These results not only indicate that BDTT-S-TR shows the lowest bimolecular recombination losses among the three systems, [24,53,58] but also demonstrate that the insertion of the meta-alkylthio substitution causes more expressed non-Langevin recombination behavior. The quite significant difference in carrier density between BDTT-O-TR and BDTT-S-TR at 1 μs delay might be indicative of an additional geminate recombination mechanism.…”

“…[16,[29][30][31][32][33] Despite tremendous efforts have been made to enhance the stability of OSCs based on the consideration of extrinsic factors like reactions with oxygen and interface degradation, [3,16,24,[34][35][36] intrinsic reactions were less frequently reported due to the complexity of separating intrinsic versus extrinsic effects. [30,37] An important intrinsic mechanism is thermal degradation because an optimal BHJ morphology was frequently found to be a metastable state which readily moves toward a less efficient thermodynamic equilibrium state.…”

A–π–D–π–A Electron‐Donating Small Molecules for Solution‐Processed Organic Solar Cells: A Review

“…Min et al synthesized a series of SMs ( m80 – m85 ) bearing DTS unit linked through bithiophene π‐bridges with electron‐withdrawing alkyldicyanovinyl groups, which revealed the effect of integrated alkyl chain engineering on morphological control. An optimized PCE of 6.4% was achieved for DTS(Oct) 2 ‐(2T‐DCV‐Me) 2 /PC 71 BM blend …”

Indacenodithienothiophene-Based Ternary Organic Solar Cells

“…Polymers and/ or small molecules, used as donor materials, in combination with fullerene derivatives, used as acceptor, are the common active components in BHJ devices (Zhang et al, 2014;Lu et al, 2015c;Min et al, 2015;Squeo et al, 2015). Due to the narrow absorption of the donor materials, one of the main challenges in order to further boost the PCE of organic solar cells is to achieve better absorption match to the solar irradiance spectrum.…”

“…In order to understand the lower FF obtained in the ternary BHJ solar cells, we first studied the charge transport properties by employing the technique of photoinduced charge carrier extraction by linearly increasing voltage (photo-CELIV) (Mozer et al, 2005;Clarke et al, 2015;Min et al, 2015). From the measured photocurrent transients, the charge carrier mobility (μ) is calculated using the following equation: …”