(A) study on highly efficient organic- and hybrid photovoltaics via control of nanomorphology

Abstract

Control of the nanomorphology in organic (polymer) - and hybrid photovoltaics is a key factor for maximizing the module power conversion efficiency (PCE) and enhancing the electrical properties related to exciton dissociation at the interfaces between donors and acceptors, diffusion of charge carriers, and charge collection at each electrode. On the other hand, although spin-coating is the most appropriate laboratory-scale film formation process, scale-up of this process does not ensure uniformity, even within a device. This makes the spin-coating process incompatible with roll-to-roll (R2R) production under ambient conditions, where the latter is desirable for suc-cessful commercialization. Here we demonstrate the nanoimprinting process incorporating a periodic nanostructure into the inverted polymer solar cells (i-PSCs) can induce a more favorable nanomorphology of BHJ layer with vertical phase segregation, effectively enhancing electrical properties as well as optical performance in i-PSCs. We additionally ap-plied various periodic nanostructures with different geometry such as period and shape, which can influence on polymer chain flow and polymer crystalline nature. And also, we propose a new approach to form high quality organic films on an aqueous substrate under ambi-ent conditions. The nanomorphology of blended films can be efficiently managed in seconds during the process of spreading on the aqueous substrate. The utility of the films in functional devices is demonstrated by applying the new film formation technique to the fabrication of highly efficient PSCs. Finally, we report the incorporation of a pristine polymer, PCDTBT with fibrills as an efficient HTL in perovskite solar cells, resulting in highly efficient device performance and high device stability. PCDTBT fibrills formed at the grain boundaries of perovskite layer provides strong adhesion and electrical paths between per-ovskite and PDCTBT layers.