A comprehensive review on the reasons behind low power conversion efficiency of dibenzo derivatives based donors in bulk heterojunction organic solar cells

Abstract

Abstract Small molecules and polymer derivatives based on fused ring system of dibenzo[b,d]thiophene, dibenzo[b,d]silole, dibenzo[b,d]furan, dibenzo[b,d]germole, dibenzo[b,d]selenophene and dibenzo[b,d]tellurophene are efficient donor (D) materials for bulk heterojunction organic solar cell (BHJ-OSCs) applications. Dibenzo based hetero-tricyclic fused ring systems showed poor PCE than other ring system due to low π-conjugation, disorder in structure, poor solubility, higher d-spacing of π-π stacking in thin film state, low hole mobility and air stability. To further improve the power conversion efficiency (PCE) of fused ring derivatives, we have to incorporate heteroatoms (P-block elements N, S, Si, Ge, Ga, Sn, and Se) and tailor three member ring based donor system. This review briefly summarizes the data on fused ring system based small molecules or polymers for BHJ-OSCs application and gives suggestion to design new donor materials with desired properties.