n-doped inorganic molecular clusters as a new type of hole transport material for efficient organic solar cells

Though organic photovoltaic cells (OPVs) have many advantages, their performance still lags far behind that of other photovoltaic platforms. One of the most fundamental reasons for this is the low charge mobility of organic materials, leading to a limit on the active layer thickness and efficient light absorption. In this work, guided by a semi-empirical model analysis and using the tandem cell strategy to overcome such issues, and taking advantage of the high diversity and easily tunable band structure of organic materials, a record and certified 17.29% power conversion efficiency for a 2-terminal monolithic solution processed tandem OPV is achieved.

A nonfullerene-based polymer solar cell (PSC) that significantly outperforms fullerene-based PSCs with respect to the power-conversion efficiency is demonstrated for the first time. An efficiency of >11%, which is among the top values in the PSC field, and excellent thermal stability is obtained using PBDB-T and ITIC as donor and acceptor, respectively.