•A 5 nm annealed seed layer of ClInPc induces triclinic phase across the entire film.•The triclinic phase of ClInPc introduce new absorption feature in the NIR region.•The triclinic phase of ClInPc improves solar cell overall performance.We demonstrate that a thin seed layer of indium phthalocyanine chloride (ClInPc) annealed under mild conditions effectively controls the morphology of both post-annealing deposited ClInPc films and ClInPc:C60 mixed films, introducing the triclinic phase into the commonly monoclinic phase dominating film. ClInPc/C60 planar solar cells and ClInPc:C60 (1:1) planar-mixed solar cells with and without the triclinic phase were studied. Increased short circuit current (Jsc), fill factor (FF), external quantum efficiency (EQE) and internal quantum efficiency (IQE) of the devices containing triclinic phase is attributed to the enhanced absorption in the near infrared (NIR) region and decreased series resistance. The correlation between open circuit voltage (Voc) and dark saturation pre-exponential factor (Jso) was analyzed to investigate Voc loss upon annealing. The overall performance of device is considerably improved by introducing the triclinic phase of ClInPc.

Highly transparent and conductive monolayer graphene was used as a template to tune the crystal orientation of pentacene from generic standing-up (001) to lying-down (022) in neat films. Spatially resolved Kelvin probe force microscopy (KPFM) was used to reveal the energy levels of pentacene thin films grown on substrates with and without the template graphene layer, as well as the energy level alignment in various pentacene-containing organic–organic heterojunctions. A correlation between crystal domain orientation and the work function was directly observed using KPFM. Up to 0.36 eV shifts in work function were observed in neat pentacene films over large areas (>0.5 in.2) upon orientation transition, likely due to the transition from Fermi level pinning (standing-up pentacene on ITO) to vacuum level alignment (lying-down pentacene on graphene–ITO). Morphology-induced energy level shifts versus interfacial electronic equilibration effects were disentangled using atomic force microscopy, KPFM, X-ray diffraction, and Raman data for neat pentacene films and pentacene containing heterojunctions on monolayer graphene. The data detailed herein provide a fundamental picture of the major interfacial effects active in optoelectronic devices containing a bare graphene electrode.