In this article, we have investigated the role of polymer regio-regularity and film fabrication technique in reducing metal diffusion from top electrodes in sandwich type devices. Poly(3-hexyl thiophene)(P3HT) polymer of varying regio-regularity was chosen for investigation and its corresponding thin films were fabricated by spin-coating(SC) and floating film transfer method(FTM). Sandwich devices with a top interface between gold and i) FTM coated regio-regular (rr) P3HT, ii) FTM coated non-regiocontrolled (nr) P3HT, iii) SC nr-P3HT and iv) SC rr-P3HT were fabricated. The current density vs voltage (J-V) characteristics of the devices revealed non-ohmic characteristics. Estimation of interfacial hole barrier heights using Fowler Nordheim tunneling model revealed a small barrier of 1.12 eV for the isotropic spin-coated nr-P3HT film which increased to 1.37 eV with an increase in film anisotropy for the FTM nr-P3HT film. The barrier height also gradually declined from 1.37 eV to 1.05 eV with increase in regioregularity from FTM nr-P3HT to FTM rr-P3HT. These observations were confirmed through optical and structural characterizations along with depth profiling of metal diffusion using XPS. Pronounced Au diffusion to a higher depth was observed in the XPS results for the highly anisotropic FTM film that decreased subsequently with decrease in anisotropy from FTM to spin-coated film. It was thus deduced that a judicious selection of fabrication technique and polymer aids in reducing metal diffusion leading to improved device performance. The results hold crucial significance towards the fabrication of efficient organic photodetectors that have a sandwich type device architecture.

在本文中，我们研究了聚合物区域规则性和薄膜制造技术在减少三明治型设备中顶部电极的金属扩散中的作用。选择具有不同区域规则性的聚（3-己基噻吩）（P3HT）聚合物进行研究，并通过旋涂（SC）和浮膜转移法（FTM）制备其相应的薄膜。制作了在金与i）FTM涂层的非区域控制（rr）P3HT，ii）FTM涂层的非区域控制（nr）P3HT，iii）SC nr-P3HT和iv）SC rr-P3HT之间具有顶部界面的三明治设备。器件的电流密度与电压（JV）特性显示出非欧姆特性。使用Fowler Nordheim隧道模型估算界面空穴势垒高度可发现1的小势垒。各向同性旋涂的nr-P3HT膜为12 eV，随着FTM nr-P3HT膜的膜各向异性的增加，其增加到1.37 eV。随着从FTM nr-P3HT到FTM rr-P3HT的区域规则性的增加，势垒高度也从1.37 eV逐渐下降到1.05 eV。这些观察结果已通过光学和结构表征以及使用XPS对金属扩散进行深度剖析得到了证实。对于高度各向异性的FTM薄膜，在XPS结果中观察到明显的Au扩散到更高的深度，随后随着从FTM到旋涂薄膜的各向异性的减小而降低。因此推断出，对制造技术和聚合物的明智选择有助于减少金属扩散，从而改善了器件性能。