Synthesis of Boron, Phosphorus, and Sulfur‐Doped Carbon Quantum Dots and Its use to Enhance the Photovoltaic Parameters of Organic Solar Cells

Herein, we used a one‐step hydrothermal method to synthesize boron, phosphorus, and sulfur‐doped carbon quantum dots (B, P, S‐CQDs) using citric acid, boric acid, phosphoric acid, and thioglycolic acid as raw ingredients. As characterized by Fourier transform infrared spectroscopy, the resulted CQDs were successfully doped by selected hetero atoms. The method yielded B, P, S‐CQDs showing a ≈39% quantum yield of photoluminescence. The transmission electron microscopy and ultraviolet–visible (UV–Vis) absorbance spectroscopy results confirmed that the B, P, S‐CQDs were found to be 4–6 nm in dimensions. Application of B, P, S‐CQDs as an additive in poly(3‐hexylthiophene‐2,5‐diyl):[6,6]‐phenyl‐C61‐butyric acid methyl ester (P3HT:PCBM) organic solar cells (OSCs) was investigated. Results revealed that the B, P, S‐CQDs‐added photoactive layer showed better light absorption, especially in UV range. The OSCs with B, P, S‐CQDs (1 vol% of B, P, S‐CQDs)‐added P3HT:PCBM layer presented higher power conversion efficiency of 1.812% with a higher fill factor of 46.5% and a short‐circuit current density ( J sc ) of 6.641 mA cm −2 . This work proposes an easy and efficient approach to improve photovoltaic performance of OSCs.