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A series of wide bandgap terpolymers are designed and synthesized, which exhibit low energetic disorders. Based on the terpolymers, outstanding PCEs of over 31% (1000 lux) for an indoor OPV cell and over 18.2% (one-sun) for an OPV cell are achieved.

By designing new terpolymers, we tuned the molecular orientation to obtain an ordered morphology with suppressed energetic disorder. Thus, we boost the PCE of all-PSCs to over 18%.

An asymmetric wide-bandgap acceptor, namely AITC, is synthesized. The large dipole moment of AITC reinforces the molecular packing in ternary blends. Single-junction and tandem OSCs yielded a remarkable PCE of 18.8% and 19.4%, respectively.

For all small-molecule-based organic solar cells (SM-OSCs), it is very challenging to obtain a nanoscale bicontinuous network structure in the active layers, so their power conversion efficiencies (PCEs) still lag behind those of the polymer-based OSCs. In this work, highly efficient SM-OSCs based on a ternary bulk heterojunction (BHJ) layer of B1:BO-2Cl:BO-4Cl were constructed. Ternary cells with the three different BO-2Cl:BO-4Cl weight ratios exhibit higher PCEs than those of B1:BO-2Cl- and B1:BO-4Cl-based binary cells. The results obtained from the transient absorption, time-resolved photoluminescence spectroscopy and device physics analysis reveal that the ternary cell with the optimal composition (B1:BO-2Cl:BO-4Cl = 1 : 0.5 : 0.5 in weight ratio) exhibits faster charge transfer processes, suppressed geminate and non-geminate charge recombination, lower energetic disorder, and higher and more symmetric carrier mobilities than the two binary cells. The transmission electron microscopy measurement results reveal that the nanoscale bicontinuous interpenetrating network with a hierarchical branched structure can be fully evolved in the BHJ layer with the optimal ternary composition. As a result, the optimal ternary cell exhibits a PCE of 17.0% (certified to be 16.9%) and a fill factor of 0.78, which are the highest values obtained for SM-OSCs.

The innovation of photoactive layer materials is crucial for improving the power conversion efficiency (PCE) of polymer solar cells (PSCs). Herein, we report two polymer donors (PBTN-o and PBTN-p), which only differ in alkyl chains substituted at sites (6,7- or 5,8-) of the naphtho[2,3-c]thiophene-4,9-dione (NTD) unit. The single crystals of both NTD monomers demonstrate that NTD with alkyl chains at the 6,7-sites has a planar NTD skeleton, and surprisingly, NTD with alkyl chains at the 5,8-sites produces a bent NTD skeleton. The bent NTD-based polymer (PBTN-p) exhibits a more twisted conjugated backbone than PBTN-o. Our comparative studies show that PBTN-p possesses suitable aggregation properties that can optimize the photoactive layer morphology in NF PSCs. In PSCs, the optimal PBTN-o:BO-4Cl-based device shows a PCE of 11.85% with a VOC of 0.84 V, JSC of 22.41 mA cm−2, and FF of 0.63. In contrast, the optimal PBTN-p:BO-4Cl-based device exhibits a better PCE of 14.10% with the same VOC of 0.84 V, and an enhanced JSC of 24.67 mA cm−2 and FF of 0.68. This work provides a new insight into BHJ morphology optimization by side chain induced polymer main chain twisting in PSCs.

The advantage of low cost makes P3HT one of the most attractive electron donors for photovoltaic applications, but the power conversion efficiency (PCE) of the P3HT-based organic solar cells (OSCs) remains low (7–8%). Herein, to modulate the phase separation morphology so as to enhance the PCE in P3HT-based OSCs, a new NFA, namely ZY-4Cl, is designed and synthesized by modifying the cyano-substituted end groups in BTP-4Cl. The P3HT:ZY-4Cl based OSC exhibits a significantly improved PCE of ∼9.5%, which is a new record for the P3HT-based OSCs. Furthermore, two model compounds, TT-CN and TT-O, are synthesized to simulate the end groups of BTP-4Cl and ZY-4Cl, respectively. The calculated Flory-Huggins interaction parameter, the DSC and the AFM results clearly indicate that the cyano-substituted compound TT-CN shows much stronger miscibility with P3HT compared to TT-O, the one without cyano groups. This molecular design strategy is also verified in the other two representative NFAs. Therefore, this work not only reports an NFA with a high PCE for P3HT-based OSCs, but also suggests guidance for the molecular design of NFAs from the aspect of morphology control.

To address the intrinsic issue of conventional porphyrin derivatives with a deficient absorption between Soret and Q bands, we designed and synthesized two porphyrin molecules (BDTP-1 and BDTP-2) bearing a meso-alkyl substituted porphyrin core, benzodithiohene (BDT) ethynylene π-bridge and end-capping ethylrhodanine derivatives. Apart from the characteristic Soret and Q bands of porphyrin macrocycle, an extra peak (521 nm for BDTP-1 and 536 nm for BDTP-2) was derived from the BDT units. Using the porphyrin small molecules as electron donors and PC71BM as an electron acceptor, the devices show broad spectral photocurrent generation with a significant contribution from greenlight-harvesting (490–550 nm), resulting in high performances with PCEs up to 7.97%.

Hybrid organic–inorganic metal halide perovskite solar cells (PSCs) have been regarded as a low-cost, high-efficiency photovoltaic technology; however, the device performance seriously depends on interfacial properties between each contact layer. The interface plays an important role in PSCs as it induces defects, trap states, charge recombination sites etc., which are detrimental to the device performance and stability. Herein, a post-treatment of self-assembling large cations of tert-butylammonium (tBA) on the surface of the perovskite layer is demonstrated as an effective strategy to passivate interface and grain boundary defects and thus improve device performance and stability. In particular, a normal hysteresis is turned into an inverted hysteresis by increasing the amount of tert-butylammonium iodide (tBAI), which can be ascribed to modified interface states. An impressive power conversion efficiency (PCE) over 20% with a significantly suppressed hysteresis is achieved via the careful control of post-treatment conditions, which shows great promise for commercialization in the future.

Ternary solar cells have been proven to be an effective way to increase the power conversion efficiency (PCE) of organic solar cells (OSCs). Up to now, research effort has mostly focused on fullerene derivatives and acceptor–donor–acceptor (A–D–A) type non-fullerene acceptor-based ternary solar cells, while perylene diimide (PDI)-based ternary devices have been rarely studied. In this contribution, we introduced a new type of ternary solar cell based on a PDI-based small-molecule acceptor (PBI-Por) and a polymer donor (PTB7-Th) with a third PDI-based polymer acceptor (PDI-V). The introduction of PDI-V into the ternary blends not only broadens the absorption of blend films but also increases the electron mobilities. As a result, a high efficiency of 9.43% was obtained for the ternary OSC, which is 20% higher than that of the binary OSC. Detailed studies indicate that PDI-V showed good compatibility with PBI-Por in the blend films, which demonstrates a promising way to fabricate high-performance PDI-based OSCs.

Supramolecular self-assembly of a novel acceptor–π–porphyrin–π–acceptor compound driven by intermolecular sulfur–sulfur interactions leads to the formation of J-aggregates composed of helical nanowire structures. These nanowires have exhibited interesting optical activity, and when utilized as a molecular electron donor with a fullerene acceptor in bulk heterojunction organic solar cells, a high photovoltaic power conversion efficiency of over 8% has been achieved.

2-Chlorophenyl isocyanate (CI) reacts with didodecyl dimethyl ammonium bromide (DDAB) functionalized graphene oxide (DDAB-GO) dispersed in ortho-dichlorobenzene under mild conditions. The CI treatment complements DDAB functionalization to further decrease the hydrophilicity of pristine GO sheets. The resulting CI–DDAB-GO exhibits improved compatibility with the conjugated polymer poly(3-hexylthiophene) (P3HT), compared to DDAB-GO. CI–DDAB-GO sheets can be homogeneously dispersed when blended with P3HT, resulting in an improved morphology compared to P3HT:DDAB-GO composites. The incorporation of CI–DDAB-GO can effectively reduce the dark current of photo-diodes based on P3HT composites, showing potential to enhance the performance of electronic devices based on conjugated polymer composites.

Non-fullerene ternary organic solar cells (OSCs) are new promising candidates for future applications in the area of organic photovoltaics. However, their low short-circuit current (JSC) values impede efforts at increasing their power conversion efficiency (PCE) levels. Maximizing the JSC is one of the critical elements for enabling high performances of OSCs. To improve the JSC of the non-fullerene ternary OSCs based on poly[[2,6′-4,8-di(5-ethylhexylthienyl)benzo[1,2-b:3,3-b]dithiophene][3-fluoro-2[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]]:3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]-dithiophene (PTB7-Th:ITIC), a polymer of poly[N-9′′-hepta-decanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT) was added to the binary system. The PCDTBT was shown to embed in both PTB7-Th and ITIC, and introduced dual Forster resonance energy transfer (FRET) effects in the resulting ternary system. In addition, the PCDTBT may have decreased the molecular coherence lengths of PTB7-Th and ITIC and influenced the charge transport. Furthermore, the PCDTBT apparently also decreased the d-spacing of the π–π stacking of PTB7-Th and ITIC, which likely increased the intermolecular charge hopping efficiency. Doping an appropriate amount of PCDTBT in the system yielded an increase in the JSC from 13.89 to 16.71 mA cm−2. The increased JSC resulted in a 15% enhancement of the PCE, which indicated that introducing dual FRET effects is an effective way to enhance the JSC and thus the performance of the OSCs.