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Semitransparent polymer solar cells (ST-PSCs) show attractive potential in power-generating windows or building-integrated photovoltaics. However, the development of ST-PSCs is lagging behind opaque PSCs because of the contradiction between device efficiency and transmission. Herein, Ag/Au alloy nanoparticles and photonic crystals (PCs) were simultaneously introduced into ST-PSCs, acting compatibly as localized surface plasmon resonances and distributed Bragg reflectors to enhance light absorption and transmission. As a result, ST-PSCs based on a hybrid PTB7-Th:PCBM active layer contribute an efficiency as high as 7.13 ± 0.15% and an average visible transmission beyond 20%, which are superior to most of the reported results. Furthermore, PCs can partly compensate valley range of transmission by balancing reflection and transmission regions, yielding a high color rendering index of 95. We believe that the idea of two light management methods compatibly enhancing the performance of ST-PSCs can offer a promising path to develop photovoltaic applications.

We investigate the effects of polytetrafluoroethylene ͑PTFE͒ on poly͑3-hexylthiophene͒:phenyl-C61-butyric acid methyl ester ͑P3HT:PCBM͒ based organic photovoltaic ͑OPV͒ devices by inserting thermally evaporated PTFE films between indium-tin-oxide ͑ITO͒ and P3HT:PCBM layers. Significant improvement in terms of open-circuit voltage, short-circuit current, and thereby in its commensurate power conversion efficiency is achieved compared to devices with poly͑3,4-ethylenedioxythiophene͒:poly͑styrene-sulfonate͒ layers. The OPVs performance enhancement is attributed to the formation of an artificial dipole layer resulting from the rich, negatively charged fluorine that facilitates the hole extraction process. This result shows the high potential of PTFE as a low cost and stable ITO buffer layer for OPV devices.

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The surface plasmon resonance (SPR) effect based on noble metal nanoparticles (NPs) such as gold(Au) and silver(Ag) has been widely investigated and demonstrated to be a breakthrough technology to further improve the power conversion efficiency (PCE) of polymer solar cells (PSCs). Herein, diametercontrolled copper (Cu) NPs were intentionally introduced into an anode buffer layer of tungsten trioxide (WO 3 ) by the thermally evaporating method, structuring a light trapping center to enhance light absorption of PSCs. The big difference of surface energy between WO 3 and Cu can induce the growth process of Cu NPs from nucleation to isolated island by controlling evaporating thickness, yielding multiple SPR centers to radiate the electromagnetic wave toward the active layer. The steady-state photoluminescence (PL) results provide direct evidence that Cu NPs-induced SPR effect can effectively enhance light absorption of the active layer at visible wavelength, leading to a significant improvement of the short current density (J sc ) by 35.3% and PCE by 37.2% for devices with 3 nm Cu. Encouragingly, the inclusion of Cu NPs simultaneously decreases device resistance determined by complex impedance spectra. We believe the low-cost, simple-fabricated evaporating method combined with SPR enhancement can pave the way to high-performance PSCs.

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