Recently, tin oxide (SnO2) nanoparticles (NPs) have attracted considerable attention as the electron transporting layer (ETL) for organic solar cells (OSCs) due to their superior electrical properties, excellent chemical stability, and compatibility with low-temperature solution fabrication. However, the rough surface of SnO2 NPs may generate numerous defects, which limits the performance of the OSCs. In this study, we introduce a perylene diimide derivative (PDINO) that could passivate the defects between SnO2 NP ETL and the active layer. Compared with the power conversion efficiency (PCE) of the pristine SnO2 ETL–based OSCs (12.7%), the PDINO-modified device delivers a significantly increased PCE of 14.9%. Overall, this novel composite ETL exhibits lowered work function, improved electron mobility, and reduced surface defects, thus increasing charge collection efficiency and restraining defect-caused molecular recombination in the OSC. Overall, this work demonstrates a strategy of utilizing the organic–inorganic hybrid ETL that has the potential to overcome the drawbacks of SnO2 NPs, thereby developing efficient and stable OSCs.

Electrochemical copolymerization of N-methylpyrrole (NMPy) and cyclopenta[2,1-b:3,4-b 0 ]dithiophene (CPDT) was performed in acetonitrile containing sodium perchlorate as a supporting electrolyte. Characterization of the resultant copolymer P(CPDTco-NMPy) was performed by cyclic voltammetry, UV-vis spectroscopy, Fourier transform infrared spectroscopy and scanning electron microscopy. The P(CPDT-co-NMPy) film has distinct electrochromic properties and exhibits four different colors (reddish brown, pale khaki, pale sea green and light blue) under various potentials. The maximum contrast (DT%) and response time of the copolymer film at 750 nm were measured as 47.0% and 2.20 s, respectively. An electrochromic device (ECD) based on P(CPDT-co-NMPy) and poly(3,4-ethylenedioxythiophene) was constructed and characterized. The optical contrast (DT%) at 630 nm was found to be 40.2%, and the response time was measured as 1.77 s. The coloration efficiency of the device was calculated to be 476 cm 2 per C at 630 nm. The ECD also has satisfactory optical memories and redox stability.

We systematically investigated the impacts of alcohol solvent treatments on the performance of non-fullerene organic solar cells (OSCs) with poly [(2,6-(4,8-bis(5-(2-ethylhexyl)]dithiophene(ITIC) as active layers. The result demonstrates that various alcohol solvents, including methanol, ethanol, n-propanol and n-butanol can bring on the improvement of device performance. Notably, when ethanol with a moderate boiling point is adopted, the power conversion efficiency can be significantly boosted to 10.53% from 8.31% (as-cast device). The performance enhancement is mainly attributed to the optimized vertical phase separation and increased charge carrier mobility of the active layer, leading to efficient charge separation and balanced charge transportation, respectively. This work indicates that alcohol solvent treatment is a facile and effective approach to improve the performance of non-fullerene OSCs.

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