High‐Performance Inverted Polymer Solar Cells: Device Characterization, Optical Modeling, and Hole‐Transporting Modifications

TLDR

High‑efficiency polymer solar cells have been demonstrated in conventional architectures, yet inverted‑structure devices lag behind despite their superior stability and roll‑to‑roll processing potential. This study investigates solution‑processed inverted PSCs using a low‑bandgap polymer PIDT‑PhanQ blended with PC71BM as the bulk heterojunction. The authors performed comprehensive device characterization and optical modeling to assess how geometry influences photovoltaic performance. By optimizing optical field distribution and exciton generation profiles, excellent performance is achieved, but inverted devices require a higher fullerene blend ratio because the exciton peak is farther from the electron‑collecting electrode, enhancing electron mobility.

Abstract

Abstract Although high power conversion efficiencies (PCE) have already been demonstrated in conventional structure polymer solar cells (PSCs), the development of high performance inverted structure polymer solar cells is still lagging behind despite their demonstrated superior stability and feasibility for roll‐to‐roll processing. To address this challenge, a detailed study of solution‐processed, inverted‐structure PSCs based on the blends of a low bandgap polymer, poly(indacenodithiophene‐ co ‐phananthrene‐quinoxaline) (PIDT‐PhanQ) and [6,6]‐phenyl‐C 71 ‐butyric acid methyl ester (PC 71 BM) as the bulk heterojunction (BHJ) layer is carried out. Comprehensive characterization and optical modeling of the resulting devices is performed to understand the effect of device geometry on photovoltaic performance. Excellent device performance can be achieved by optimizing the optical field distribution and spatial profiles of excitons generation within the active layer in different device configurations. In the inverted structure, because the peak of the excitons generation is located farther away from the electron‐collecting electrode, a higher blending ratio of fullerene is required to provide higher electron mobility in the BHJ for achieving good device performance.