Polymer/copper indium sulfide (CIS) nanocomposite solar cells are prepared via a capper free in situ preparation route using copper and indium xanthates as precursors, which decompose and form CIS nanoparticles in the polymer matrix during a mild thermal treatment. The solar cells generate current in a wide range of the solar spectrum and exhibit efficiencies up to 2.8%.

The dissociation of photogenerated excitons and the subsequent spatial separation of the charges are of crucial importance to the design of efficient donor-acceptor heterojunction solar cells. While huge progress has been made in understanding charge generation at all-organic junctions, the process in hybrid organic:inorganic systems has barely been addressed. Here, we explore the influence of energetic driving force and local crystallinity on the efficiency of charge pair generation at hybrid organic:inorganic semiconductor heterojunctions. We use x-ray diffraction, photoluminescence quenching, transient absorption spectroscopy, photovoltaic device and electroluminescence measurements to demonstrate that the dissociation of photogenerated polaron pairs at hybrid heterojunctions is assisted by the presence of crystalline electron acceptor domains. We propose that such domains encourage delocalization of the geminate pair state. The present findings suggest that the requirement for a large driving energy for charge separation is relaxed when a more crystalline electron acceptor is used.

Hybrid solar cells based upon organic-inorganic semiconductor heterojunctions are currently the subject of signifi cant interest as they incorporate the attractive properties of both organic and inorganic materials, including the ability to tune both the electronic and structural properties over a wide range using solution-based fabrication methods. [1][2][3][4][5][6][7] A confi guration of particular promise is the hybrid inorganic nanocrystalpoly mer bulk heterojunction solar cell. A typical device consists of a photoactive layer composed of a blend of inorganic nanoparticles and a semiconducting polymer, which is sandwiched between two charge-collecting electrodes. The operation of such a system is based upon a photoinduced charge separation reaction at the inorganic-organic semiconductor heterojunction, followed by charge carrier transport and collection at the device electrodes. To date, a variety of inorganic semiconductors have been used in solution processed polymer solar cells including metal oxides, sulfi des and selenides. Metal chalcogenide nanocrystals are especially attractive for use in photovoltaic device applications as they offer the potential to extend the light harvesting capability of the device into the near infrared region of the solar spectrum. For example, impressive solar-light to electrical power conversion effi ciencies have been recently reported for photovoltaic devices based upon CdSe:PCPDTBT ( > 3%) [ 5 , 8 ] and CdS:P3HT nanocomposite fi lms (4.1%). [ 6 ] Key challenges to the design of high-performance hybrid solar cells are (i) the development of new fabrication routes for hybrid thin fi lms that enable the achievement of high yields of charge separation whilst maintaining good electrical connectivity between the inorganic nanocrystals in the photoactive layer and (ii) the development of alternative inorganic electron acceptors that exhibit light harvesting properties superior to the typically used cadmium-based materials. To address challenge (i), we have recently reported a new approach to the fabrication of hybrid metal sulfi de-polymer solar cell photoactive layers, which is based upon the in-situ thermal decomposition of a single source metal xanthate precursor in a polymer fi lm. [ 9 ] The use of metal xanthate (or metal o-alkyl dithiocarbonate) precursors for the in-situ growth of metal sulfi de nanocrystals in polymer fi lms is of particular interest due to their high solubility, low decomposition temperature and the volatility of the side products generated upon thermal decomposition. As such, we have implemented this design strategy in the fabrication of CdS:P3HT and CuInS 2 :polymer nanocomposite fi lms and demonstrated effi cient charge photogeneration at the donor-acceptor heterojunction. [9][10][11] Furthermore, the integration of such photoactive layers into solar cell architectures yielded impressive power conversion effi ciencies approaching 3% under AM1.5 simulated solar illumination. [ 11 ] In this paper, we extend our previous work and report on a bulk hete...

In this paper, indium-doped zinc oxide (IZO) films were grown by spray pyrolysis, using zinc acetate and indium acetylacetonate precursors. The focus was on developing a solution recipe based on water as solvent, with only minor acetic acid content, as well as keeping the substrate temperature as low as possible-at 360°C. The process is therefore environment friendly and energy efficient. Despite the challenging conditions, the resulting IZO films were highly transparent and conductive. Their texture deviates strongly from the (002) texture of ZnO and depends on the indium content, which also influences the resistivity. The latter attains its minimum for an indium concentration of 4 at.% in the solution and decreases for increasing film thickness, reaching the value of (5.0 ± 0.1) 9 10 -3 X cm, mainly due to the increase in carrier mobility. The stability of the resistivity after high dose of UV irradiation was found to increase with the carrier density and the film thickness. Thick, highly doped films show minimal resistivity modification even after a total dose of 12.1 kJ/cm 2 UVA/ UVB irradiation. Finally, to demonstrate its applicability in devices, the IZO electrode was used for the fabrication of a lead-perovskite absorber solar cell, yielding an energy conversion efficiency of 6% and 910 mV open-circuit voltage.

We present a thorough study on the various impacts of polymer:nanoparticle ratios on morphology, charge generation and device performance in hybrid solar cells, comprising active layers consisting of a conjugated polymer and in situ prepared copper indium sulfide (CIS) nanoparticles. We conducted morphological studies through transmission electron microscopy and transient absorption measurements to study charge generation in absorber layers with polymer:nanoparticle weight ratios ranging from 1:3 to 1:15. These data are correlated to the characteristic parameters of the prepared solar cells. To gain a deeper understanding of our experimental findings, three-dimensional drift-diffusion-based simulations were performed. Based on elaborate descriptions of the contributions of polymer and nanoparticle phase to device performances, our results suggest that a polymer:CIS volume ratio of 1:2 (weight ratio 1:9) is necessary to obtain a balanced hole and electron percolation. Also at higher CIS loadings the photocurrent remains surprisingly high due to the contribution of the CIS phase to the charge carrier generation.