Interface engineering has been proved to be a practical strategy to enhance power conversion efficiency (PCE) and stability of perovskite solar cells. Recently approaches involving ultra-thin layer deposition and vacuum-processing, while improving PCE, increase the processing complexity, and thus the overall cost. In this paper, we demonstrate a high-efficiency inverted planar perovskite solar cell, obtained with a simple wet-chemistry based, room-temperature, and cost-effective process, which synthesizes two interfacial layers: solution processed molybdenum oxide (named s-MoOx) for anode and titanium(IV) oxide bis(2,4-pentanedionate) (TOPD) for cathode buffer layers. Steady-state photoluminescence (PL), time resolved photoluminescence (TRPL) and electrochemical impedance spectroscopy (EIS) are conducted to characterize the charge transport properties, confirming an enhanced charge extraction efficiency and a suppressed charge recombination. In addition, the introduction of the interfacial layers facilities formation of an ohmic contact with the metal electrode, reducing the charge transfer resistance and increasing the FF to as high as 80.7%. The optimized solar cells achieve the best PCE of 16.04% which far exceeds the PCE of devices without these interfacial layers (PCE = 11.2%).

•Micropatterning of lanthanide edifices on flexible sheets has been reported.•Visible red/green emissions were observed.•The luminescent silicone stamps exhibited pH dependence.Based on lanthanide optical materials, flexible and transparent luminescent films have been fabricated based on self-cracking micro-pattern on polydimethylsiloxane (PDMS) substrates. The morphology and photoluminescence were studied based on the self-assembly structures. The corresponding intra-molecular energy transfer and photophysical properties were evaluated. Results demonstrated that both lanthanide complex and phosphors could be well controlled and stamped onto the designed cracking micropatterns with red or green emissions. The effects of pH value changes on the luminescent features of the films, as well as its influence on europium complex have been extensively studied. Investigation on transmittance and mechanical properties indicated that the optical and structural quality of such functional films will be potentially useful in the novel design of light-emitting devices or for sensing applications.We reported micromolding technique for the patterning of lanthanide luminescent layers onto robust sheets. Europium antibiotic complex, BaMoO4:Eu3+ and CePO4:Tb3+ have been incorporated into the substrate with the aid of self-cracking of egg white film.Download high-res image (92KB)Download full-size image

•A series of TPE derivatives containing tetrafluorobutylenedioxy “loops” were synthesized.•The photoluminescence emission under mechanical grinding and thermal treatment show AIE and MFC properties.•Tetrafluorobutylenedioxy “loops” control the balance between weak intermolecular interactions.A series of tetraphenylethylenes (TPE) derivatives in which one or more of the phenyl rings have been replaced by a fused fluorine containing 2,3,4,5-tetrahydrobenzo[b][1,4]dioxocane unit have been synthesized. The analysis of the photoluminescence emission under application of mechanical grinding and thermal treatment show that in addition to the expected aggregation induced emission behavior observed in solution, these simple modifications of the TPE system confer mechanofluorochromic properties to the corresponding materials. The results of X-ray diffraction and theoretical calculations suggest that the introduction of tetrafluorobutylenedioxy “loops” control the balance between weak intermolecular interactions and thus the interconversion between “macro” and “micro-aggregates” which is proposed as the basic mechanism for the observed MFC properties.

•New donor polymers with PCEs of ∼10% have been achieved.•A donor polymer with ultralow band gap of 1.27 eV has been proved.•PBE0/6-311G (d,p) and TD-B3LYP/6-31G (d,p) were reliable method to predict energy levels of polymers.•Introduction of electron-withdrawing functional groups is proved to be an efficient strategy for OSCs.Extending conjugation length, involving strong π–π interactions and large electron-withdrawing functional groups have been experimentally proved to be the efficient strategies for performance enhancement of donor–acceptor (D–A) polymers used in organic solar cells. In this paper, considering above strategies, a series of novel D–A conjugated polymers have been designed and theoretically investigated on their electronic structures, energy levels, and optical absorption, using first principles calculation methods under the PBE0/6-311G (d,p) and TD-B3LYP/6-31G (d,p) level. The results show, compared with those base polymers, the newly designed polymers exhibit better performances including narrower band gaps, deeper HOMO energy levels (broadband optical absorption), and better theoretical power conversion efficiencies (PCEs) predicted by Scharber diagrams. These polymers can be used as the active layers in high performance organic solar cells.

We theoretically designed four new A-A-D-A-A type electron donors by side-by-side combination of strong electron-withdrawing groups. The electronic structures and optical absorption spectra of donors were calculated using density functional theory (DFT) and time-dependent DFT (TDDFT) at the 6-31G∗ level, respectively. The results show that the calculations are in good agreement with the experiments on electronic structures and optical spectra. The designed molecules exhibit good properties with low band gap, low LUMO energy level, and broad light absorption. Moreover, the estimated solar cell efficiency is up to ∼10% when these donors are used in combination with PCBM as an acceptor.Graphical abstractHighlights► Donors with estimated PCE of ∼10% are theoretically achieved. ► The side-by-side combination of electron-withdrawing groups attributes to donor. ► (TD) DFT/6-31G∗ calculations predict reliably energy levels and band gaps.

Conjugated polymers with donor–acceptor architectures have been successfully applied in bulk heterojunction solar cell devices. Tuning the electron-withdrawing capability in donor–acceptor (D–A) conjugated polymers allows for design of new polymers with enhanced electrical and optical properties. In this paper, a series of D–A copolymers, PBDFDTBT (P1a), PBDTDTBT (P2a), PNDTDTBT (P3a), and PQDTDTBT (P4a), were selected and theoretically investigated using PBE0/6-311G** and TD-PBE0/6-311G**//PBE0/6-311G** methods. The calculated results agree well with the available experimental data of HOMO energy levels and band gaps. We further designed and studied four novel copolymers, P1b, P2b, P3b, and P4b, by substituting the 2,1,3-benzothiadiazole (BT) unit in P1a–P4a with a stronger unit of naphtho[1,2-c:5,6-c]bis[1,2,5]thiadiazole (NT), respectively. Compared with P1a–P4a, the newly designed polymers of P1b–P4b show better performance with the smaller band gaps and lower HOMO energy levels. The PCEs of ∼5%, ∼7%, ∼7%, and ∼7% for P1b–P4b, predicted by Scharber diagrams, are much higher than those of P1a–P4a when used in combination with PCBM. These results clearly reveal that tuning the electron-withdrawing capability in D–A conjugated polymers is an effective way to improve the electrical and optical properties and the efficiency of the photovoltaic device.