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have been successfully synthesized by annealing three precursor film samples deposited via a modified successive ionic layer adsorption and reaction (SILAR) method. The mechanism of ion-exchange and improvement of the rinsing procedure were introduced into the SILAR process for the purpose of achieving the codeposition of different metal sulfides and increasing the growth rate of thin films. The crystal structure, composition, surface morphology, optical and electrical properties of three ternary sulfide samples have been characterized. The temperature dependence of the Seebeck coefficient, electrical conductivity, thermal conductivity and ZT values of the Cu 3 SnS 4 thin film sample have also been measured between 293 K and 573 K. Owing to the intrinsic advantages of the SILAR method and the improvement of the SILAR process, ternary Cu-Sn-S thin films can be deposited on glass substrates at a speed of 400 nm per hour and the surface morphologies of the thin films are comparable with those of thin films prepared by vacuum based methods, which can satisfy the requirements for high quality, high efficiency and low-cost production of thin films. With the appropriate band gap energies (1.0 eV, 1.45 eV and 1.47 eV for Cu 2 SnS 3 , Cu 5 Sn 2 S 7 and Cu 3 SnS 4 respectively) and considerable absorption coefficients (a > 10 4 cm À1 ), most importantly with earth-abundant elements, Cu-Sn-S thin films can be used as alternative absorber layer materials in thin film solar cells. Additionally for the Cu 5 Sn 2 S 7 and Cu 3 SnS 4 film samples, some novel properties (such as strong optical absorption in the NIR band, excellent conductivity and suitable carrier concentration) make them attractive for potential research interest as thermoelectric materials.

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Charge transport, extraction, and collection play important roles in the working process of organic solar cells (OSCs), and the interface engineering is one of the key factors to realize the high-throughput printing fabrication of OSCs. The structure design or doping of electrode interlayer materials can effectively suppress the recombination of carriers at the interface and improve the ohmic contact between the active layer and the electrodes, which is a useful method to achieve a high power conversion efficiency (PCE). Poly­(9,9-bis­(3′-(N,N-dimethyl)-N-ethylammoniumpropyl-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene))­dibromide (PFN-Br) is a widely used alcohol-soluble cathode interlayer material. By doping PFN-Br with melamine (MA), the charge extraction efficiency and nongeminate recombination at the cathode interface are successfully optimized. Finally, the device efficiencies of PM6:Y6 and PM6:BTP-eC9 are increased to an amazing 17.44% and 18.58%, respectively. This work provides a new strategy for the fabrication of high-efficiency OSCs.

A facile sol-gel and selenization process has been demonstrated to fabricate high-quality single-phase earth abundant kesterite Cu2ZnSn(S,Se)4 (CZTSSe) photovoltaic absorbers. The structure and band gap of the fabricated CZTSSe can be readily tuned by varying the [S]/([S] + [Se]) ratios via selenization condition control. The effects of [S]/([S] + [Se]) ratio on device performance have been presented. The best device shows 8.25% total area efficiency without antireflection coating. Low fill factor is the main limitation for the current device efficiency compared to record efficiency device due to high series resistance and interface recombination. By improving film uniformity, eliminating voids, and reducing the Mo(S,Se)2 interfacial layer, a further boost of the device efficiency is expected, enabling the proposed process for fabricating one of the most promising candidates for kesterite solar cells.

Cu 2 ZnSnS 4 nanowires and nanotubes have been synthesized via a modified sol-gel solution approach with AAO templates. The prepared nanowires and nanotubes have been characterized and show the typical morphology of nanostructure and properties of kesterite CZTS, which can provide the potential application and research for low-dimension solar cells.

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