CsPbI2Br Quantum Dots Integration for High Performance Organic Photovoltaics and Photodetectors

Abstract

Organic semiconductors promise highly-flexible, solution-processable electronics, and have attracted great attentions in applications photovoltaics and photodetectors. However, they also suffer from large exciton binding energy and poor charge transport ability, making them uncomparable with the traditional inorganic alternatives. In this work, CsPbI2Br inorganic perovskite quantum dots (PQDs) were integrated into the cutting-edge polymer:non-fullerene photoactive films to improve the performance of both photovoltaic (PV) and photodetecting (PD) devices. We find there is a strong energy transfer from these PQDs to the donor component PM6 which resutls in improved short-circuit current and photo-responsivity in PV and PD devices, whilst strong chemical interactions between PQDs and non-fullerene acceptors L8-BO was also revealled, passivating the defects of PQDs. Mott-Schottky measurements, in conjunction with the electrochemical impedance spectroscopy, further elucidate that a wilder depletion region was established with the assistence of PQDs, attributing to the above morphology moduclation and larger dielectric constant enabled by PQDs, which could be the key to the accelerated charge transport and reduced charge recombination. With the integration of PQDs, improved power conversion efficiency from 18.8 ％ to 19.4 ％ (maximum 20.2 % for D18:L8-BO) was observed in PM6:L8-BO PV devices, whilst decreased dark current from 1.5 × 10-5 to 9.6 × 10-7 mA cm-2 at - 0.1 V was also obtained in PD devices, translating to a superior detectivity of 6.5 × 1012 Jones at 770 nm.