# Enhanced Photovoltaic Performance of Ternary Small Molecule/Polymer Bulk Heterojunction Solar Cells

## TL;DR

This paper shows how adding a polymer donor to a solar cell blend improves efficiency by enhancing light absorption and charge transport.

## Contribution

The novel use of a polymer donor in a ternary blend to improve solar cell performance through optimized morphology and energy levels.

## Key findings

- A ternary blend increased power conversion efficiency from 7.99% to 9.08%.
- PBDTTT-EFT enhances nanomorphology and forms a cascade energy level for better charge mobility.
- Polymer donors can control absorption, transport, and exciton dissociation in organic solar cells.

## Abstract

We report a notable enhancement in the performance of small-molecule-based organic photovoltaics (OPVs) through the use of a ternary blend comprising a small-molecule donor (DTS(FBTTh2)2), a polymer donor (PBDTTT-EFT), and a fullerene acceptor (PC71BM). By optimizing the composition of this ternary active layer, we achieved a significant increase in power conversion efficiency from 7.99% to 9.08%. This improvement is attributed to the broader light absorption spectrum and enhanced charge transport pathways provided by the polymeric donor. PBDTTT-EFT optimizes the nanomorphology and ordering of the bulk heterojunction films and forms a cascade energy level that enhances charge carrier mobility. Our results demonstrate that semiconducting polymer donors can effectively control light absorption, charge transport, and exciton dissociation by optimizing morphology and crystallinity. This approach offers new possibilities for advancing the performance of various optoelectronic devices through strategic use of different semiconducting polymer donors.