# Morphology-controlled synthesis of CuCo2S4 as a high-efficiency counter electrode via a precursor-directed strategy for quantum dot-sensitized solar cells (QDSSCs)

## TL;DR

This paper introduces a new method to create CuCo2S4 materials with different shapes, which improves the efficiency of solar cells.

## Contribution

A precursor-directed solvothermal method is introduced to synthesize morphology-controlled CuCo2S4 without templates.

## Key findings

- Flower-like CuCo2S4 achieved the highest power conversion efficiency of 7.42% in QDSSCs.
- Flower-like CuCo2S4 showed the lowest charge transfer resistance (0.076 Ω) and best electrocatalytic activity.
- Morphology control significantly impacts the performance of counter electrodes in solar cells.

## Abstract

Quantum dot-sensitized solar cells (QDSSCs) have emerged as promising photovoltaic devices, in which the counter electrode (CE) plays a crucial role in the catalytic reduction of Sn2− and charge transfer. Based on a precursor-directed strategy, this study reports a simple and cost-effective solvothermal method for the synthesis of morphology-controlled CuCo2S4 nanomaterials without templates and structure-directing agents, including flower-like (f-CuCo2S4), nanosheet-like (n-CuCo2S4), nanoparticle-like (p-CuCo2S4), and microsphere-like (m-CuCo2S4) structures. The effects of CuCo2S4 CEs with different morphologies on the photovoltaic performance of QDSSCs were also systematically investigated. Among them, the f-CuCo2S4 CE exhibited the highest specific surface area and the best catalytic performance, resulting in a power conversion efficiency (PCE) of 7.42% for QDSSCs, which is 55% higher than that of materials with other morphologies. Electrochemical analysis confirmed that it delivered the lowest charge transfer resistance (Rct = 0.076 Ω) and the highest electrocatalytic activity. This work highlights the importance of morphology control for optimizing the performance of CEs for efficient QDSSCs.

Different morphologies of CuCo2S4-CEs were synthesized through a precursor-directed strategy; the QDSSCs based on f-CuCo2S4-CEs achieve a PCE of 7.42%.