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Abstract Photodetectors that can sense not only light intensity but also light's polarization state add valuable information that is beneficial in a wide array of applications. Polymer semiconductors are an attractive material system to achieve intrinsic polarization sensitivity due to their anisotropic optoelectronic properties. In this report, the thermomechanical properties of the polymer semiconductors PBnDT‐FTAZ and P(NDI2OD‐T2) are leveraged to realize bulk heterojunction (BHJ) films with record in‐plane alignment. Two polymer blends with distinct weight average molar masses (Mw) are considered and either a strain‐ or rub‐alignment process is applied to align the polymer blend films. Optimized processing yields films with dichroic ratios (DR) of over 11 for the highMwsystem and nearly 17 for the lowMwsystem. Incorporating the aligned films into photodetectors results in a polarized photocurrent ratio of 15.25 with corresponding anisotropy ratio of 0.88 at a wavelength of 530 nm, representing the highest reported photocurrent ratio for photodiodes that can operate in a self‐powered regime. The demonstrated performance showcases the ability of polymer semiconductors to achieve BHJ films with exceptional in‐plane polymer alignment, enabling high performance polarization sensitive photodetectors for incorporation into novel device architectures. 

Abstract In this report, a high‐performance all‐polymer organic photodetector that is sensitive to linearly polarized light throughout the visible spectrum is demonstrated. The active layer is a bulk heterojunction composed of an electron donor polymer PBnDT‐FTAZ and acceptor polymer P(NDI2OD‐T2) that have complementary spectral absorption resulting in efficient detection from 350 to 800 nm. The blend film exhibits good ductility with the ability to accommodate large strains of over 60% without fracture. This allows the film to undergo large uniaxial strain resulting in in‐plane alignment of both polymers making the film optically anisotropic and intrinsically polarization sensitive. The films are characterized by UV–vis spectroscopy and grazing incidence wide‐angle X‐ray scattering showing that both polymers have similar in‐plane backbone alignment and maintain packing order after being strained. The films are integrated into devices and characterized under linear polarized light. The strain‐oriented detectors have maximum photocurrent anisotropies of 1.4 under transverse polarized light while maintaining peak responsivities of 0.21 A W⁻¹and a 3 dB cutoff frequency of ≈1 kHz. The demonstrated performance is comparable to the current state of the art all‐polymer photodetectors with the added capability of polarization sensitivity enabling new application opportunities. 

Abstract Tandem structure provides a practical way to realize high efficiency organic photovoltaic cells, it can be used to extend the wavelength coverage for light harvesting. The interconnecting layer (ICL) between subcells plays a critical role in the reproducibility and performance of tandem solar cells, yet the processability of the ICL has been a challenge. In this work the fabrication of highly reproducible and efficient tandem solar cells by employing a commercially available material, PEDOT:PSS HTL Solar (HSolar), as the hole transporting material used for the ICL is reported. Comparing with the conventional PEDOT:PSS Al 4083 (c‐PEDOT), HSolar offers a better wettability on the underlying nonfullerene photoactive layers, resulting in better charge extraction properties of the ICL. When FTAZ:IT‐M and PTB7‐Th:IEICO‐4F are used as the subcells, a power conversion efficiency (PCE) of 14.7% is achieved in the tandem solar cell. To validate the processability of these tandem solar cells, three other research groups have successfully fabricated tandem devices using the same recipe and the highest PCE obtained is 16.1%. With further development of donor polymers and device optimization, the device simulation results show that a PCE > 22% can be realized in tandem cells in the near future.