Efficient Carrier Multiplication in Low Band Gap Mixed Sn/Pb Halide Perovskites

Abstract

Carrier multiplication (CM) generates multiple electron–hole pairs in a semiconductor from a single absorbed photon with energy exceeding twice the band gap. Thus, CM provides a promising way to circumvent the Shockley–Queisser limit of solar cells. The ideal material for CM should have significant overlap with the solar spectrum and should be able to fully utilize the excess energy above the band gap for additional charge carrier generation. We report efficient CM in mixed Sn/Pb halide perovskites (band gap of 1.28 eV) with onset just above twice the band gap. The CM rate outcompetes the carrier cooling process leading to efficient CM with a quantum yield of 2 for photoexcitation at 2.8 times the band gap. Such efficient CM characteristics add to the many advantageous properties of mixed Sn/Pb metal halide perovskites for photovoltaic applications.

Optoelectronic Properties of Low‐Bandgap Halide Perovskites for Solar Cell Applications

“…Very recently, the carrier multiplication (CM) phenomenon has been studied in (FASnI 3 ) 0.6 (MAPbI 3 ) 0.4 thin films, which shows that the CM rate outcompetes the slower carrier cooling process. [ 108 ] As a result, efficient CM was demonstrated with a quantum yield of 2 at 2.8 times the optical bandgap. Moreover, the occurrence of a CM threshold close to twice the bandgap led the authors to speculate that the excess energy is asymmetrically distributed between the electron and the hole due to the presence of a second conduction (valence) band near twice the bandgap.…”

Unravelling the Underlying Hot Carrier Transfer and Relaxation Pathways in Type-1 CsPbBr3–PbS System

“…All inorganic perovskites have so far established themselves as the most potential photovoltaic materials due to the impressive candidature showcased by them. , However, apart from CsPbI 3 , which serves the utmost prospect of exploiting the low-energy regime of the spectral range (near-infrared), the usage of other all-inorganic members in photovoltaic devices is still limited because of the intermediate energy band gaps offered by these contenders, but that does not conclude the list of hindrances that avert the practical applicability of the all-inorganic perovskites. , There is a further major dilemma that holds back the deployment of CsPbI 3 , “its poor stability”. , One way of banishing such obstacles is using other all-inorganic perovskites in conjunction with low band gap materials.…”

Lead‐Free Halide Double Perovskites: Fundamentals, Challenges, and Photovoltaics Applications

“…It is well known that materials suitable for solar cells should show a bandgap situated within 1.0–1.6 eV, excellent charge transport properties, and strong chemical stability. [ 33 ] Several HDPs have acceptable bandgaps that satisfy the Shockley–Queisser limit requirement. In addition, in double perovskites, the substitution of various components significantly changes the electronic band structure, bandgap range, and the transition nature (direct or indirect).…”

“…[ 43 ] This crystal's time‐resolved PL spectra at room temperature demonstrate that the parity‐allowable transitions have a short PL lifetime, while a longer PL lifetime is observed in the parity‐forbidden transitions. [ 33b,44 ] Figure 5c shows the nine types of HDPs designed, six of which had a direct bandgap. Five types from this six‐compound showed inversion‐symmetry‐induced parity prohibited transitions, which prevent these materials from being used in PV applications.…”