Non-fullerene all-small-molecule organic solar cells (NFSM-OSCs) have shown potential as OSCs, owing to their high purity, easy synthesis and good reproducibility. However, challenges in the modulation of phase separation morphology have limited their development. Herein, two novel small molecular donors, BTEC-1F and BTEC-2F, derived from the small molecule DCAO3TBDTT, are synthesized. Using Y6 as the acceptor, devices based on non-fluorinated DCAO3TBDTT showed an open circuit voltage (Voc) of 0.804 V and a power conversion efficiency (PCE) of 10.64 %. Mono-fluorinated BTEC-1F showed an increased Voc of 0.870 V and a PCE of 11.33 %. The fill factor (FF) of di-fluorinated BTEC-2F-based NFSM-OSC was improved to 72.35 % resulting in a PCE of 13.34 %, which is higher than that of BTEC-1F (61.35 %) and DCAO3TBDTT (60.95 %). To our knowledge, this is the highest PCE for NFSM-OSCs. BTEC-2F had a more compact molecular stacking and a lower crystallinity which enhanced phase separation and carrier transport. 相似文献
Indacenodithiophene (IDT) derivatives are kinds of the most representative and widely used cores of small molecule acceptors (SMAs) in organic solar cells (OSCs). Here we systematically investigate the influence of end-group fluorination density and position on the photovoltaic properties of the IDT-based SMAs IDIC-nF (n = 0, 2, 4). The absorption edge of IDIC-nF red-shifts with the π-π stacking and crystallinity improvement, and their electronic energy levels downshift with increasing n. Due to the advantages of Jsc and FF as well as acceptable Voc, the difluorinated IDIC-2F acceptor based OSCs achieve the highest power conversion efficiency (PCE) of 13%, better than the OSC devices based on IDIC and IDIC-4F as acceptors. And the photovoltaic performance of the PTQ10: IDIC-2F OSCs is insensitive to the active layer thickness: PCE still keep high values of 12.00% and 11.46% for the devices with active layer thickness of 80 and 354 nm, respectively. This work verifies that fine and delicate modulation of the SMAs molecular structure could optimize photovoltaic performance of the corresponding OSCs. Meanwhile, the thickness-insensitivity property of the OSCs has potential for large-scale and printable fabrication technology. 相似文献
A novel hole‐transporting molecule (F101) based on a furan core has been synthesized by means of a short, high‐yielding route. When used as the hole‐transporting material (HTM) in mesoporous methylammonium lead halide perovskite solar cells (PSCs) it produced better device performance than the current state‐of‐the‐art HTM 2,2′,7,7′‐tetrakis‐(N,N‐di‐p‐methoxyphenylamine)‐9,9′‐spirobifluorene (spiro‐OMeTAD). The F101‐HTM‐based device exhibited both slightly higher Jsc (19.63 vs. 18.41 mA cm?2) and Voc (1.1 vs. 1.05 V) resulting in a marginally higher power conversion efficiency (PCE) (13.1 vs. 13 %). The steady‐state and time‐resolved photoluminescence show that F101 has significant charge extraction ability. The simple molecular structure, short synthesis route with high yield and better performance in devices makes F101 an excellent candidate for replacing the expensive spiro‐OMeTAD as HTM in PSCs. 相似文献
The synthesis, characterization, and photophysical and photovoltaic properties of two anthracene‐containing wide‐band‐gap donor and acceptor (D–A) alternating conjugated polymers ( P1 and P2 ) are described. These two polymers absorb in the range of 300–600 nm with a band gap of about 2.12 eV. Polymer solar cells with P1 :PC71BM as the active layer demonstrate a power conversion efficiency (PCE) of 2.23% with a high Voc of 0.96 V, a Jsc of 4.4 mA cm−2, and a comparable fill factor (FF) of 0.53 under simulated solar illumination of AM 1.5 G (100 mW cm−2). In addition, P2 :PC71BM blend‐based solar cells exhibit a PCE of 1.42% with a comparable Voc of 0.89 V, a Jsc of 3.0 mA cm−2, and an FF of 0.53.
A pentacyclic benzodipyrrolothiophene ( BDPT ) unit, in which two outer thiophene rings are covalently fastened with the central phenylene ring by nitrogen bridges, was synthesized. The two pyrrole units embedded in BDPT were constructed by using one‐pot palladium‐catalyzed amination. The coplanar stannylated Sn‐BDPT building block was copolymerized with electron‐deficient thieno[3,4‐c]pyrrole‐4,6‐dione ( TPD ), benzothiadiazole ( BT ), and dithienyl‐diketopyrrolopyrrole ( DPP ) acceptors by Stille polymerization. The bridging nitrogen atoms make the BDPT motif highly electron‐abundant and structurally coplanar, which allows for tailoring the optical and electronic properties of the resultant polymers. Strong photoinduced charge‐transfer with significant band‐broadening in the solid state and relatively higher oxidation potential are characteristic of the BDPT‐based polymers. Poly(benzodipyrrolothiophene‐alt‐benzothiadiazole) ( PBDPTBT ) achieved the highest field‐effect hole mobility of up to 0.02 cm2 V?1 s?1. The photovoltaic device using the PBDPTBT /PC71BM blend (1:3, w/w) exhibited a Voc of 0.6 V, a Jsc of 10.34 mA cm?2, and a FF of 50 %, leading to a decent PCE of 3.08 %. Encouragingly, the device incorporating poly(benzodipyrrolothiophene‐alt‐thienopyrrolodione) ( PBDPTTPD )/PC71BM (1:3, w/w) composite delivered a highest PCE of 3.72 %. The enhanced performance arises from the lower‐lying HOMO value of PBDPTTPD to yield a higher Voc of 0.72 V. 相似文献
A series of simple phenothiazine‐based dyes, namely, TP , EP , TTP , ETP , and EEP have been developed, in which the thiophene (T), ethylenedioxythiophene (E), their dimers, and mixtures are present to modulate dye aggregation, charge recombination, and dye regeneration for highly efficient dye‐sensitized solar cell (DSSC) applications. Devices sensitized by the dyes TP and TTP display high power conversion efficiencies (PCEs) of 8.07 (Jsc=15.2 mA cm?2, Voc=0.783 V, fill factor (FF)=0.679) and 7.87 % (Jsc=16.1 mA cm?2, Voc=0.717 V, FF=0.681), respectively; these were measured under simulated AM 1.5 sunlight in conjunction with the I?/I3? redox couple. By replacing the T group with the E unit, EP ‐based DSSCs had a slightly lower PCE of 7.98 % with a higher short‐circuit photocurrent (Jsc) of 16.7 mA cm?2. The dye ETP , with a mixture of E and T, had an even lower PCE of 5.62 %. Specifically, the cell based on the dye EEP , with a dimer of E, had inferior Jsc and Voc values and corresponded to the lowest PCE of 2.24 %. The results indicate that the photovoltaic performance can be finely modulated through structural engineering of the dyes. The selection of T analogues as donors can not only modulate light absorption and energy levels, but also have an impact on dye aggregation and interfacial charge recombination of electrons at the interface of titania, electrolytes, and/or oxidized dye molecules; this was demonstrated through DFT calculations, electrochemical impedance analysis, and transient photovoltage studies. 相似文献
We have developed a ladder‐type dithienocyclopentathieno[3,2‐b]thiophene ( DTCTT ) hexacyclic unit in which the central thieno[3,2‐b]thiophene ring was covalently fastened to two adjacent thiophene rings through carbon bridges, thereby forming two connected cyclopentadithiophene ( CPDT ) units in a hexacyclic coplanar structure. This stannylated Sn‐DTCTT building block was copolymerized with three electron‐deficient acceptors, dibromo‐thieno[3,4‐c]pyrrole‐4,6‐dione ( TPD ), dibromo‐benzothiadiazole ( BT ), and dibromo‐phenanthrenequinoxaline ( PQX ), by Stille polymerization, thereby furnishing a new class of alternating donor–acceptor copolymers: PDTCTTTPD , PDTCTTBT , and PDTCTTPQX , respectively. Field‐effect transistors based on PDTCTTPQX and PDTCTTBT yielded high hole mobilities of 0.017 and 0.053 cm2 V?1 s?1, respectively, which are among the highest performances among amorphous donor–acceptor copolymers. A bulk heterojunction solar cell that incorporated PDTCTTTPD with the lower‐lying HOMO energy level delivered a higher Voc value of 0.72 V and a power conversion efficiency (PCE) value of 2.59 %. 相似文献
A new broad bandgap and 2D‐conjugated D‐A copolymer, PBDTBTz‐T , based on bithienyl‐benzodithiophene donor unit and bithiazole (BTz) acceptor unit, is designed and synthesized for the application as donor material in polymer solar cells (PSCs). The polymer possesses highly coplanar and crystalline structure with a higher hole mobility and lower HOMO energy level which is beneficial to achieve higher open circuit voltage (Voc) of the PSCs with the polymer as donor. The PSCs based on PBDTBTz‐T :PC71BM blend film with a lower PC71BM content of 40% demonstrate a power conversion efficiency (PCE) of 6.09% with a relatively higher Voc of 0.92 V. These results indicate that the lower HOMO energy level of the BTz‐based D–A copolymer is beneficial to a high Voc of the PSCs. The polymer, with highly coplanar and crystalline structure, can effectively reduce the content of fullerene acceptor in the active layer and can enhance the absorption and PCE of the PSCs.
To achieve high open-circuit voltage (Voc) and low acceptor content, the molecular design of a small-molecule donor with low energy loss (Eloss) is very important for solution-processable organic solar cells (OSCs). Herein, we designed and synthesized a new coplanar A−D−A structured organic small-molecule semiconductor with non-fused ring structure π-bridge, namely B2TPR , and applied it as donor material in OSCs. Owing to the strong electron-withdrawing effect of the end group and the coplanar π-bridge, B2TPR exhibits a low-lying highest occupied molecular orbital and strong crystallinity. Furthermore, benefiting from the coplanar molecular skeleton, the high hole mobility, balanced charge transport and reduced recombination were achieved, leading to a high fill factor (FF). The OSCs based on B2TPR : PC71BM blend film (w/w=1 : 0.35) demonstrates a moderate power conversion efficiency (PCE) of 7.10 % with a remarkable Voc of 0.98 V and FF of 64 %, corresponding to a low fullerene content of 25.9 % and a low Eloss of 0.70 eV. These results demonstrate the great potential of small-molecule with structure of B2TPR for future low-cost organic photovoltaic applications. 相似文献
Two new electron‐rich molecules based on 3,4‐phenylenedioxythiophene (PheDOT) were synthesized and successfully adopted as hole‐transporting materials (HTMs) in perovskite solar cells (PSCs). X‐ray diffraction, absorption spectra, photoluminescence spectra, electrochemical properties, thermal stabilities, hole mobilities, conductivities, and photovoltaic parameters of PSCs based on these two HTMs were compared with each other. By introducing methoxy substituents into the main skeleton, the energy levels of PheDOT‐core HTM were tuned to match with the perovskite, and its hole mobility was also improved (1.33×10?4 cm2 V?1 s?1, being higher than that of spiro‐OMeTAD, 2.34×10?5 cm2 V?1 s?1). The PSC based on MeO‐PheDOT as HTM exhibits a short‐circuit current density (Jsc) of 18.31 mA cm?2, an open‐circuit potential (Voc) of 0.914 V, and a fill factor (FF) of 0.636, yielding an encouraging power conversion efficiency (PCE) of 10.64 % under AM 1.5G illumination. These results give some insight into how the molecular structures of HTMs affect their performances and pave the way for developing high‐efficiency and low‐cost HTMs for PSCs. 相似文献
A series of heteroleptic bis(tridentate) RuII complexes featuring N^C^N‐cyclometalating ligands is presented. The 1,2,3‐triazole‐containing tridentate ligands are readily functionalized with hydrophobic side chains by means of click chemistry and the corresponding cyclometalated RuII complexes are easily synthesized. The performance of these thiocyanate‐free complexes in a dye‐sensitized solar cell was tested and a power conversion efficiency (PCE) of up to 4.0 % (Jsc=8.1 mA cm?2, Voc=0.66 V, FF=0.70) was achieved, while the black dye ((NBu4)3[Ru(Htctpy)(NCS)3]; Htctpy=2,2′:6′,2′′‐terpyridine‐4′‐carboxylic acid‐4,4′′‐dicarboxylate) showed 5.2 % (Jsc=10.7 mA cm?2, Voc=0.69 V, FF=0.69) under comparable conditions. When co‐adsorbed with chenodeoxycholic acid, the PCE of the best cyclometalated dye could be improved to 4.5 % (Jsc=9.4 mA cm?2, Voc=0.65 V, FF=0.70). The PCEs correlate well with the light‐harvesting capabilities of the dyes, while a comparable incident photon‐to‐current efficiency was achieved with the cyclometalated dye and the black dye. Regeneration appeared to be efficient in the parent dye, despite the high energy of the highest occupied molecular orbital. The device performance was investigated in more detail by electrochemical impedance spectroscopy. Ultimately, a promising RuII sensitizer platform is presented that features a highly functionalizable “click”‐derived cyclometalating ligand. 相似文献
Achieving both high open-circuit voltage (Voc) and short-circuit current density (Jsc) to boost power-conversion efficiency (PCE) is a major challenge for organic solar cells (OSCs), wherein high energy loss (Eloss) and inefficient charge transfer usually take place. Here, three new Y-series acceptors of mono-asymmetric asy-YC11 and dual-asymmetric bi-asy-YC9 and bi-asy-YC12 are developed. They share the same asymmetric D1AD2 (D1=thieno[3,2-b]thiophene and D2=selenopheno[3,2-b]thiophene) fused-core but have different unidirectional sidechain on D1 side, allowing fine-tuned molecular properties, such as intermolecular interaction, packing pattern, and crystallinity. Among the binary blends, the PM6 : bi-asy-YC12 one has better morphology with appropriate phase separation and higher order packing than the PM6 : asy-YC9 and PM6 : bi-asy-YC11 ones. Therefore, the PM6 : bi-asy-YC12-based OSCs offer a higher PCE of 17.16 % with both high Voc and Jsc, due to the reduced Eloss and efficient charge transfer properties. Inspired by the high Voc and strong NIR-absorption, bi-asy-YC12 is introduced into efficient binary PM6 : L8-BO to construct ternary OSCs. Thanks to the broadened absorption, optimized morphology, and furtherly minimized Eloss, the PM6 : L8-BO : bi-asy-YC12-based OSCs achieve a champion PCE of 19.23 %, which is one of the highest efficiencies among these annealing-free devices. Our developed unidirectional sidechain engineering for constructing bi-asymmetric Y-series acceptors provides an approach to boost PCE of OSCs. 相似文献
We report a new small molecular acceptor, ITIC‐OEG, which is based on indacenodithieno[3,2‐b]thiophene and 1,1‐(dicyanomethylene)‐3‐ indanone including oligoethyleneglycol (OEG) side‐chains. ITIC‐OEG was found to have higher dielectric constant (εr=5.6) than that of a reference molecule of ITIC with normal alkyl substituents (εr=3.9). The dielectric constant of medium influences significantly the exciton binding energy and the resulting charge separation and recombination. The optical, electrochemical and morphological properties of ITIC‐OEG and its photovoltaic characteristics were investigated by blending with a semi‐crystalline donor polymer, PPDT2FBT, with comparison to those of ITIC. ITIC‐OEG shows more red‐shifted absorption and stronger crystalline packing than ITIC. However, the lower photovoltaic performance (with 1.58% power conversion efficiency, PCE) was measured for PPDT2FBT:ITIC‐OEG, compared to PPDT2FBT:ITIC (5.52% PCE). The incompatibility between PPDT2FBT and ITIC‐OEG (due to high hydrophilic nature of OEG chains) resulted in poor intermixing with large domain separation over 300 nm, showing inefficient charge separation and significant charge recombination. Therefore, to investigate the effect of dielectric constant of the materials on the charge separation and recombination, the blend morphology of the PPDT2FBT:ITIC‐OEG should be optimized first by improving their miscibility and phase separation. 相似文献
How the conjugated polymers affect the crystallization of DR3TBDTT, in addition to the corresponding morphology and performance, is not well understood. In this work, the weakly crystalline polymer PTB7‐Th and highly crystalline polymers of PCDTBT and P3HT were incorporated into DR3TBDTT:PC71BM system to investigate the variation of crystallization, morphology and performance. It is demonstrated that PTB7‐Th is the most effective additive to improve the PCE value of DR3TBDTT:PC71BM to 5.7%, showing the nucleating agent reducing the crystallization correlation length (CCL) value of DR3TBDTT from 18.7 nm to 17.0 nm, in addition to the optimized morphology. In contrast, the PCDTBT and P3HT could induce the crystallization of DR3TBDTT, leading to much higher CCL value as well as obvious phase separation. Despite of energy level alignment, the crystallization of DR3TBDTT influenced by polymers determines the corresponding morphology of active layers and photovoltaic performance. 相似文献
Effect of the device fabrication conditions on photovoltaic performance of the polymer solar cells based on poly(3‐hexylthiophene) (P3HT) as donor and indene‐C70 bisadduct (IC70BA) as acceptor was studied systematically. The device fabrication conditions we studied include pre‐thermal annealing temperature, active layer thickness, and the P3HT:IC70BA weight ratios. For devices with a 188‐nm‐thick active layer of P3HT:IC70BA (1:1, w:w) blend film and pre‐thermal annealing at 150°C for 10 min, maximum power conversion efficiency (PCE) reached 5.82% with Voc of 0.81 V, Isc of 11.37 mA/cm2, and FF of 64.0% under the illumination of AM1.5G, 100 mW/cm2. 相似文献
In dye‐sensitized solar cells (DSSCs), a significant dye‐regeneration force (ΔGreg0≥0.5 eV) is usually required for effective dye regeneration, which results in a major energy loss and limits the energy‐conversion efficiency of state‐of‐art DSSCs. We demonstrate that when dye molecules and redox couples that possess similar conjugated ligands are used, efficient dye regeneration occurs with zero or close‐to‐zero driving force. By using Ru(dcbpy)(bpy)22+ as the dye and Ru(bpy)2(MeIm)23+//2+ as the redox couple, a short‐circuit current (Jsc) of 4 mA cm?2 and an open‐circuit voltage (Voc) of 0.9 V were obtained with a ΔGreg0 of 0.07 eV. The same was observed for the N3 dye and Ru(bpy)2(SCN)21+/0 (ΔGreg0=0.0 eV), which produced an Jsc of 2.5 mA cm?2 and Voc of 0.6 V. Charge recombination occurs at pinholes, limiting the performance of the cells. This proof‐of‐concept study demonstrates that high Voc values can be attained by significantly curtailing the dye‐regeneration force. 相似文献