Effect of acceptor strength on optical, electrochemical and photovoltaic properties of phenothiazine-based small molecule for bulk heterojunction organic solar cells

Benzoselenadiazole‐core asymmetric D‐A‐A small molecule for solution processed bulk heterojunction organic solar cells

“…Generally, the performance of BHJ-OSCs is governed by the relative concentrations of acceptor and donor materials used in blended layer which results in the generation of photoexcited charge carriers and their subsequent charge transport in the active layer. 57 From Figure 5A, the BHJ-OSC device with an active layer of RT-BSe-F:PC 60 BM (1:2, wt/wt) blend thin film shows a high J SC = 12.56 mA cm −2 , V OC = 0.71 V and FF = 0.42, resulting in considerable PCE of $3.75%. On the other hand, the low PCEs of $2.50% and $3.06% are observed for the BHJ-OSC device fabricated with RT-BSe-F:PC 60 BM (1:1 and 1:3, wt/wt) blend thin films, respectively.…”

Structure-induced optoelectronic properties of phenothiazine-based materials

“…In one study, they developed two symmetrical A-p-D-p-A configured oligomers 26 and 27 with a BDT as a central donor core, PTZ as a p-conjugated bridge, and malononitrile or 1,3-indandione as terminal acceptor units. 16 Devices based on 27 showed higher PCE than those employing 26 owing to the high hole mobility, better nanoscale morphology, and more controlled interpenetrating network. In another study, the same authors synthesized three asymmetrical small molecules (28)(29)(30) with an identical triphenylamine-phenothiazine conjugate backbone but end-capped with different acceptors, namely 3-ethylrhodanine (Rh), malononitrile (MN) and 1,3-indandione (IND).…”

“…For instance, D-A chromophores can be built by covalently attaching electron-withdrawing (EW) or donating groups at C-3 and C-7 positions. 16,28 The N-10 active site can be decorated with alkyl, oligo, aryl, or aralkyl groups to induce solutionprocessable properties and/or to modify the degree of crystallinity and/or to influence the packing motif. 22 Similarly, aromatic S-heterocycles can be easily oxidized/reduced to achieve sulphur in different oxidation states (sulphide, sulfoxide, or sulfone) and to affect the redox and spectroscopic properties.…”

“…Furthermore, Weng et al also prepared a series of small molecules based on A-D-A and A-D-D-A type configuration with the PTZ as a core and studied the correlation between different end groups Table 1. The effect of molecular configuration, optoelectronic properties, carrier mobilities, morphology, and PV properties on the molecular design of oligomers based on PTZ moiety was explored in detail by Revoju et al 16,28 In particular, the authors studied the tuning of the end groups in the molecular structures and its effect on the electron-accepting ability and polarity. In one study, they developed two symmetrical A-p-D-p-A configured oligomers 26 and 27 with a BDT as a central donor core, PTZ as a p-conjugated bridge, and malononitrile or 1,3-indandione as terminal acceptor units.…”

“…The presence of electron-rich sulphur and nitrogen heteroatoms and the ionization potential of 6.73 eV is well suited for constructing the D-A materials with enhanced ICT characteristics. [13][14][15][16] The nonplanar structure of PTZs, with a dihedral angle of 158.51 between the planes of two benzene rings, is responsible for the ability to suppress molecular aggregation and intramolecular excimer formation. 15,17,18 For example, PTZ-derivatives substituted at C 3, 7-positions are involved in two-electron reactions whereas N-10 substituted can only donate one electron.…”